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bf0f6f24 IM |
1 | /* |
2 | * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH) | |
3 | * | |
4 | * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
5 | * | |
6 | * Interactivity improvements by Mike Galbraith | |
7 | * (C) 2007 Mike Galbraith <efault@gmx.de> | |
8 | * | |
9 | * Various enhancements by Dmitry Adamushko. | |
10 | * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com> | |
11 | * | |
12 | * Group scheduling enhancements by Srivatsa Vaddagiri | |
13 | * Copyright IBM Corporation, 2007 | |
14 | * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> | |
15 | * | |
16 | * Scaled math optimizations by Thomas Gleixner | |
17 | * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de> | |
21805085 PZ |
18 | * |
19 | * Adaptive scheduling granularity, math enhancements by Peter Zijlstra | |
90eec103 | 20 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra |
bf0f6f24 IM |
21 | */ |
22 | ||
1983a922 | 23 | #include <linux/sched.h> |
cb251765 | 24 | #include <linux/latencytop.h> |
3436ae12 | 25 | #include <linux/cpumask.h> |
83a0a96a | 26 | #include <linux/cpuidle.h> |
029632fb PZ |
27 | #include <linux/slab.h> |
28 | #include <linux/profile.h> | |
29 | #include <linux/interrupt.h> | |
cbee9f88 | 30 | #include <linux/mempolicy.h> |
e14808b4 | 31 | #include <linux/migrate.h> |
cbee9f88 | 32 | #include <linux/task_work.h> |
029632fb PZ |
33 | |
34 | #include <trace/events/sched.h> | |
35 | ||
36 | #include "sched.h" | |
9745512c | 37 | |
bf0f6f24 | 38 | /* |
21805085 | 39 | * Targeted preemption latency for CPU-bound tasks: |
bf0f6f24 | 40 | * |
21805085 | 41 | * NOTE: this latency value is not the same as the concept of |
d274a4ce IM |
42 | * 'timeslice length' - timeslices in CFS are of variable length |
43 | * and have no persistent notion like in traditional, time-slice | |
44 | * based scheduling concepts. | |
bf0f6f24 | 45 | * |
d274a4ce IM |
46 | * (to see the precise effective timeslice length of your workload, |
47 | * run vmstat and monitor the context-switches (cs) field) | |
2b4d5b25 IM |
48 | * |
49 | * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds) | |
bf0f6f24 | 50 | */ |
2b4d5b25 IM |
51 | unsigned int sysctl_sched_latency = 6000000ULL; |
52 | unsigned int normalized_sysctl_sched_latency = 6000000ULL; | |
2bd8e6d4 | 53 | |
1983a922 CE |
54 | /* |
55 | * The initial- and re-scaling of tunables is configurable | |
1983a922 CE |
56 | * |
57 | * Options are: | |
2b4d5b25 IM |
58 | * |
59 | * SCHED_TUNABLESCALING_NONE - unscaled, always *1 | |
60 | * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus) | |
61 | * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus | |
62 | * | |
63 | * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus)) | |
1983a922 | 64 | */ |
2b4d5b25 | 65 | enum sched_tunable_scaling sysctl_sched_tunable_scaling = SCHED_TUNABLESCALING_LOG; |
1983a922 | 66 | |
2bd8e6d4 | 67 | /* |
b2be5e96 | 68 | * Minimal preemption granularity for CPU-bound tasks: |
2b4d5b25 | 69 | * |
864616ee | 70 | * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds) |
2bd8e6d4 | 71 | */ |
2b4d5b25 IM |
72 | unsigned int sysctl_sched_min_granularity = 750000ULL; |
73 | unsigned int normalized_sysctl_sched_min_granularity = 750000ULL; | |
21805085 PZ |
74 | |
75 | /* | |
2b4d5b25 | 76 | * This value is kept at sysctl_sched_latency/sysctl_sched_min_granularity |
b2be5e96 | 77 | */ |
0bf377bb | 78 | static unsigned int sched_nr_latency = 8; |
b2be5e96 PZ |
79 | |
80 | /* | |
2bba22c5 | 81 | * After fork, child runs first. If set to 0 (default) then |
b2be5e96 | 82 | * parent will (try to) run first. |
21805085 | 83 | */ |
2bba22c5 | 84 | unsigned int sysctl_sched_child_runs_first __read_mostly; |
bf0f6f24 | 85 | |
bf0f6f24 IM |
86 | /* |
87 | * SCHED_OTHER wake-up granularity. | |
bf0f6f24 IM |
88 | * |
89 | * This option delays the preemption effects of decoupled workloads | |
90 | * and reduces their over-scheduling. Synchronous workloads will still | |
91 | * have immediate wakeup/sleep latencies. | |
2b4d5b25 IM |
92 | * |
93 | * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) | |
bf0f6f24 | 94 | */ |
2b4d5b25 IM |
95 | unsigned int sysctl_sched_wakeup_granularity = 1000000UL; |
96 | unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL; | |
bf0f6f24 | 97 | |
2b4d5b25 | 98 | const_debug unsigned int sysctl_sched_migration_cost = 500000UL; |
da84d961 | 99 | |
afe06efd TC |
100 | #ifdef CONFIG_SMP |
101 | /* | |
102 | * For asym packing, by default the lower numbered cpu has higher priority. | |
103 | */ | |
104 | int __weak arch_asym_cpu_priority(int cpu) | |
105 | { | |
106 | return -cpu; | |
107 | } | |
108 | #endif | |
109 | ||
ec12cb7f PT |
110 | #ifdef CONFIG_CFS_BANDWIDTH |
111 | /* | |
112 | * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool | |
113 | * each time a cfs_rq requests quota. | |
114 | * | |
115 | * Note: in the case that the slice exceeds the runtime remaining (either due | |
116 | * to consumption or the quota being specified to be smaller than the slice) | |
117 | * we will always only issue the remaining available time. | |
118 | * | |
2b4d5b25 IM |
119 | * (default: 5 msec, units: microseconds) |
120 | */ | |
121 | unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; | |
ec12cb7f PT |
122 | #endif |
123 | ||
3273163c MR |
124 | /* |
125 | * The margin used when comparing utilization with CPU capacity: | |
893c5d22 | 126 | * util * margin < capacity * 1024 |
2b4d5b25 IM |
127 | * |
128 | * (default: ~20%) | |
3273163c | 129 | */ |
2b4d5b25 | 130 | unsigned int capacity_margin = 1280; |
3273163c | 131 | |
8527632d PG |
132 | static inline void update_load_add(struct load_weight *lw, unsigned long inc) |
133 | { | |
134 | lw->weight += inc; | |
135 | lw->inv_weight = 0; | |
136 | } | |
137 | ||
138 | static inline void update_load_sub(struct load_weight *lw, unsigned long dec) | |
139 | { | |
140 | lw->weight -= dec; | |
141 | lw->inv_weight = 0; | |
142 | } | |
143 | ||
144 | static inline void update_load_set(struct load_weight *lw, unsigned long w) | |
145 | { | |
146 | lw->weight = w; | |
147 | lw->inv_weight = 0; | |
148 | } | |
149 | ||
029632fb PZ |
150 | /* |
151 | * Increase the granularity value when there are more CPUs, | |
152 | * because with more CPUs the 'effective latency' as visible | |
153 | * to users decreases. But the relationship is not linear, | |
154 | * so pick a second-best guess by going with the log2 of the | |
155 | * number of CPUs. | |
156 | * | |
157 | * This idea comes from the SD scheduler of Con Kolivas: | |
158 | */ | |
58ac93e4 | 159 | static unsigned int get_update_sysctl_factor(void) |
029632fb | 160 | { |
58ac93e4 | 161 | unsigned int cpus = min_t(unsigned int, num_online_cpus(), 8); |
029632fb PZ |
162 | unsigned int factor; |
163 | ||
164 | switch (sysctl_sched_tunable_scaling) { | |
165 | case SCHED_TUNABLESCALING_NONE: | |
166 | factor = 1; | |
167 | break; | |
168 | case SCHED_TUNABLESCALING_LINEAR: | |
169 | factor = cpus; | |
170 | break; | |
171 | case SCHED_TUNABLESCALING_LOG: | |
172 | default: | |
173 | factor = 1 + ilog2(cpus); | |
174 | break; | |
175 | } | |
176 | ||
177 | return factor; | |
178 | } | |
179 | ||
180 | static void update_sysctl(void) | |
181 | { | |
182 | unsigned int factor = get_update_sysctl_factor(); | |
183 | ||
184 | #define SET_SYSCTL(name) \ | |
185 | (sysctl_##name = (factor) * normalized_sysctl_##name) | |
186 | SET_SYSCTL(sched_min_granularity); | |
187 | SET_SYSCTL(sched_latency); | |
188 | SET_SYSCTL(sched_wakeup_granularity); | |
189 | #undef SET_SYSCTL | |
190 | } | |
191 | ||
192 | void sched_init_granularity(void) | |
193 | { | |
194 | update_sysctl(); | |
195 | } | |
196 | ||
9dbdb155 | 197 | #define WMULT_CONST (~0U) |
029632fb PZ |
198 | #define WMULT_SHIFT 32 |
199 | ||
9dbdb155 PZ |
200 | static void __update_inv_weight(struct load_weight *lw) |
201 | { | |
202 | unsigned long w; | |
203 | ||
204 | if (likely(lw->inv_weight)) | |
205 | return; | |
206 | ||
207 | w = scale_load_down(lw->weight); | |
208 | ||
209 | if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST)) | |
210 | lw->inv_weight = 1; | |
211 | else if (unlikely(!w)) | |
212 | lw->inv_weight = WMULT_CONST; | |
213 | else | |
214 | lw->inv_weight = WMULT_CONST / w; | |
215 | } | |
029632fb PZ |
216 | |
217 | /* | |
9dbdb155 PZ |
218 | * delta_exec * weight / lw.weight |
219 | * OR | |
220 | * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT | |
221 | * | |
1c3de5e1 | 222 | * Either weight := NICE_0_LOAD and lw \e sched_prio_to_wmult[], in which case |
9dbdb155 PZ |
223 | * we're guaranteed shift stays positive because inv_weight is guaranteed to |
224 | * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22. | |
225 | * | |
226 | * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus | |
227 | * weight/lw.weight <= 1, and therefore our shift will also be positive. | |
029632fb | 228 | */ |
9dbdb155 | 229 | static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw) |
029632fb | 230 | { |
9dbdb155 PZ |
231 | u64 fact = scale_load_down(weight); |
232 | int shift = WMULT_SHIFT; | |
029632fb | 233 | |
9dbdb155 | 234 | __update_inv_weight(lw); |
029632fb | 235 | |
9dbdb155 PZ |
236 | if (unlikely(fact >> 32)) { |
237 | while (fact >> 32) { | |
238 | fact >>= 1; | |
239 | shift--; | |
240 | } | |
029632fb PZ |
241 | } |
242 | ||
9dbdb155 PZ |
243 | /* hint to use a 32x32->64 mul */ |
244 | fact = (u64)(u32)fact * lw->inv_weight; | |
029632fb | 245 | |
9dbdb155 PZ |
246 | while (fact >> 32) { |
247 | fact >>= 1; | |
248 | shift--; | |
249 | } | |
029632fb | 250 | |
9dbdb155 | 251 | return mul_u64_u32_shr(delta_exec, fact, shift); |
029632fb PZ |
252 | } |
253 | ||
254 | ||
255 | const struct sched_class fair_sched_class; | |
a4c2f00f | 256 | |
bf0f6f24 IM |
257 | /************************************************************** |
258 | * CFS operations on generic schedulable entities: | |
259 | */ | |
260 | ||
62160e3f | 261 | #ifdef CONFIG_FAIR_GROUP_SCHED |
bf0f6f24 | 262 | |
62160e3f | 263 | /* cpu runqueue to which this cfs_rq is attached */ |
bf0f6f24 IM |
264 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
265 | { | |
62160e3f | 266 | return cfs_rq->rq; |
bf0f6f24 IM |
267 | } |
268 | ||
62160e3f IM |
269 | /* An entity is a task if it doesn't "own" a runqueue */ |
270 | #define entity_is_task(se) (!se->my_q) | |
bf0f6f24 | 271 | |
8f48894f PZ |
272 | static inline struct task_struct *task_of(struct sched_entity *se) |
273 | { | |
9148a3a1 | 274 | SCHED_WARN_ON(!entity_is_task(se)); |
8f48894f PZ |
275 | return container_of(se, struct task_struct, se); |
276 | } | |
277 | ||
b758149c PZ |
278 | /* Walk up scheduling entities hierarchy */ |
279 | #define for_each_sched_entity(se) \ | |
280 | for (; se; se = se->parent) | |
281 | ||
282 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) | |
283 | { | |
284 | return p->se.cfs_rq; | |
285 | } | |
286 | ||
287 | /* runqueue on which this entity is (to be) queued */ | |
288 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) | |
289 | { | |
290 | return se->cfs_rq; | |
291 | } | |
292 | ||
293 | /* runqueue "owned" by this group */ | |
294 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
295 | { | |
296 | return grp->my_q; | |
297 | } | |
298 | ||
3d4b47b4 PZ |
299 | static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
300 | { | |
301 | if (!cfs_rq->on_list) { | |
9c2791f9 VG |
302 | struct rq *rq = rq_of(cfs_rq); |
303 | int cpu = cpu_of(rq); | |
67e86250 PT |
304 | /* |
305 | * Ensure we either appear before our parent (if already | |
306 | * enqueued) or force our parent to appear after us when it is | |
9c2791f9 VG |
307 | * enqueued. The fact that we always enqueue bottom-up |
308 | * reduces this to two cases and a special case for the root | |
309 | * cfs_rq. Furthermore, it also means that we will always reset | |
310 | * tmp_alone_branch either when the branch is connected | |
311 | * to a tree or when we reach the beg of the tree | |
67e86250 PT |
312 | */ |
313 | if (cfs_rq->tg->parent && | |
9c2791f9 VG |
314 | cfs_rq->tg->parent->cfs_rq[cpu]->on_list) { |
315 | /* | |
316 | * If parent is already on the list, we add the child | |
317 | * just before. Thanks to circular linked property of | |
318 | * the list, this means to put the child at the tail | |
319 | * of the list that starts by parent. | |
320 | */ | |
321 | list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list, | |
322 | &(cfs_rq->tg->parent->cfs_rq[cpu]->leaf_cfs_rq_list)); | |
323 | /* | |
324 | * The branch is now connected to its tree so we can | |
325 | * reset tmp_alone_branch to the beginning of the | |
326 | * list. | |
327 | */ | |
328 | rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; | |
329 | } else if (!cfs_rq->tg->parent) { | |
330 | /* | |
331 | * cfs rq without parent should be put | |
332 | * at the tail of the list. | |
333 | */ | |
67e86250 | 334 | list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list, |
9c2791f9 VG |
335 | &rq->leaf_cfs_rq_list); |
336 | /* | |
337 | * We have reach the beg of a tree so we can reset | |
338 | * tmp_alone_branch to the beginning of the list. | |
339 | */ | |
340 | rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; | |
341 | } else { | |
342 | /* | |
343 | * The parent has not already been added so we want to | |
344 | * make sure that it will be put after us. | |
345 | * tmp_alone_branch points to the beg of the branch | |
346 | * where we will add parent. | |
347 | */ | |
348 | list_add_rcu(&cfs_rq->leaf_cfs_rq_list, | |
349 | rq->tmp_alone_branch); | |
350 | /* | |
351 | * update tmp_alone_branch to points to the new beg | |
352 | * of the branch | |
353 | */ | |
354 | rq->tmp_alone_branch = &cfs_rq->leaf_cfs_rq_list; | |
67e86250 | 355 | } |
3d4b47b4 PZ |
356 | |
357 | cfs_rq->on_list = 1; | |
358 | } | |
359 | } | |
360 | ||
361 | static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) | |
362 | { | |
363 | if (cfs_rq->on_list) { | |
364 | list_del_rcu(&cfs_rq->leaf_cfs_rq_list); | |
365 | cfs_rq->on_list = 0; | |
366 | } | |
367 | } | |
368 | ||
b758149c PZ |
369 | /* Iterate thr' all leaf cfs_rq's on a runqueue */ |
370 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ | |
371 | list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) | |
372 | ||
373 | /* Do the two (enqueued) entities belong to the same group ? */ | |
fed14d45 | 374 | static inline struct cfs_rq * |
b758149c PZ |
375 | is_same_group(struct sched_entity *se, struct sched_entity *pse) |
376 | { | |
377 | if (se->cfs_rq == pse->cfs_rq) | |
fed14d45 | 378 | return se->cfs_rq; |
b758149c | 379 | |
fed14d45 | 380 | return NULL; |
b758149c PZ |
381 | } |
382 | ||
383 | static inline struct sched_entity *parent_entity(struct sched_entity *se) | |
384 | { | |
385 | return se->parent; | |
386 | } | |
387 | ||
464b7527 PZ |
388 | static void |
389 | find_matching_se(struct sched_entity **se, struct sched_entity **pse) | |
390 | { | |
391 | int se_depth, pse_depth; | |
392 | ||
393 | /* | |
394 | * preemption test can be made between sibling entities who are in the | |
395 | * same cfs_rq i.e who have a common parent. Walk up the hierarchy of | |
396 | * both tasks until we find their ancestors who are siblings of common | |
397 | * parent. | |
398 | */ | |
399 | ||
400 | /* First walk up until both entities are at same depth */ | |
fed14d45 PZ |
401 | se_depth = (*se)->depth; |
402 | pse_depth = (*pse)->depth; | |
464b7527 PZ |
403 | |
404 | while (se_depth > pse_depth) { | |
405 | se_depth--; | |
406 | *se = parent_entity(*se); | |
407 | } | |
408 | ||
409 | while (pse_depth > se_depth) { | |
410 | pse_depth--; | |
411 | *pse = parent_entity(*pse); | |
412 | } | |
413 | ||
414 | while (!is_same_group(*se, *pse)) { | |
415 | *se = parent_entity(*se); | |
416 | *pse = parent_entity(*pse); | |
417 | } | |
418 | } | |
419 | ||
8f48894f PZ |
420 | #else /* !CONFIG_FAIR_GROUP_SCHED */ |
421 | ||
422 | static inline struct task_struct *task_of(struct sched_entity *se) | |
423 | { | |
424 | return container_of(se, struct task_struct, se); | |
425 | } | |
bf0f6f24 | 426 | |
62160e3f IM |
427 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
428 | { | |
429 | return container_of(cfs_rq, struct rq, cfs); | |
bf0f6f24 IM |
430 | } |
431 | ||
432 | #define entity_is_task(se) 1 | |
433 | ||
b758149c PZ |
434 | #define for_each_sched_entity(se) \ |
435 | for (; se; se = NULL) | |
bf0f6f24 | 436 | |
b758149c | 437 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
bf0f6f24 | 438 | { |
b758149c | 439 | return &task_rq(p)->cfs; |
bf0f6f24 IM |
440 | } |
441 | ||
b758149c PZ |
442 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
443 | { | |
444 | struct task_struct *p = task_of(se); | |
445 | struct rq *rq = task_rq(p); | |
446 | ||
447 | return &rq->cfs; | |
448 | } | |
449 | ||
450 | /* runqueue "owned" by this group */ | |
451 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
452 | { | |
453 | return NULL; | |
454 | } | |
455 | ||
3d4b47b4 PZ |
456 | static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
457 | { | |
458 | } | |
459 | ||
460 | static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) | |
461 | { | |
462 | } | |
463 | ||
b758149c PZ |
464 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
465 | for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) | |
466 | ||
b758149c PZ |
467 | static inline struct sched_entity *parent_entity(struct sched_entity *se) |
468 | { | |
469 | return NULL; | |
470 | } | |
471 | ||
464b7527 PZ |
472 | static inline void |
473 | find_matching_se(struct sched_entity **se, struct sched_entity **pse) | |
474 | { | |
475 | } | |
476 | ||
b758149c PZ |
477 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
478 | ||
6c16a6dc | 479 | static __always_inline |
9dbdb155 | 480 | void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec); |
bf0f6f24 IM |
481 | |
482 | /************************************************************** | |
483 | * Scheduling class tree data structure manipulation methods: | |
484 | */ | |
485 | ||
1bf08230 | 486 | static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime) |
02e0431a | 487 | { |
1bf08230 | 488 | s64 delta = (s64)(vruntime - max_vruntime); |
368059a9 | 489 | if (delta > 0) |
1bf08230 | 490 | max_vruntime = vruntime; |
02e0431a | 491 | |
1bf08230 | 492 | return max_vruntime; |
02e0431a PZ |
493 | } |
494 | ||
0702e3eb | 495 | static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) |
b0ffd246 PZ |
496 | { |
497 | s64 delta = (s64)(vruntime - min_vruntime); | |
498 | if (delta < 0) | |
499 | min_vruntime = vruntime; | |
500 | ||
501 | return min_vruntime; | |
502 | } | |
503 | ||
54fdc581 FC |
504 | static inline int entity_before(struct sched_entity *a, |
505 | struct sched_entity *b) | |
506 | { | |
507 | return (s64)(a->vruntime - b->vruntime) < 0; | |
508 | } | |
509 | ||
1af5f730 PZ |
510 | static void update_min_vruntime(struct cfs_rq *cfs_rq) |
511 | { | |
b60205c7 PZ |
512 | struct sched_entity *curr = cfs_rq->curr; |
513 | ||
1af5f730 PZ |
514 | u64 vruntime = cfs_rq->min_vruntime; |
515 | ||
b60205c7 PZ |
516 | if (curr) { |
517 | if (curr->on_rq) | |
518 | vruntime = curr->vruntime; | |
519 | else | |
520 | curr = NULL; | |
521 | } | |
1af5f730 PZ |
522 | |
523 | if (cfs_rq->rb_leftmost) { | |
524 | struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost, | |
525 | struct sched_entity, | |
526 | run_node); | |
527 | ||
b60205c7 | 528 | if (!curr) |
1af5f730 PZ |
529 | vruntime = se->vruntime; |
530 | else | |
531 | vruntime = min_vruntime(vruntime, se->vruntime); | |
532 | } | |
533 | ||
1bf08230 | 534 | /* ensure we never gain time by being placed backwards. */ |
1af5f730 | 535 | cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); |
3fe1698b PZ |
536 | #ifndef CONFIG_64BIT |
537 | smp_wmb(); | |
538 | cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; | |
539 | #endif | |
1af5f730 PZ |
540 | } |
541 | ||
bf0f6f24 IM |
542 | /* |
543 | * Enqueue an entity into the rb-tree: | |
544 | */ | |
0702e3eb | 545 | static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 IM |
546 | { |
547 | struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; | |
548 | struct rb_node *parent = NULL; | |
549 | struct sched_entity *entry; | |
bf0f6f24 IM |
550 | int leftmost = 1; |
551 | ||
552 | /* | |
553 | * Find the right place in the rbtree: | |
554 | */ | |
555 | while (*link) { | |
556 | parent = *link; | |
557 | entry = rb_entry(parent, struct sched_entity, run_node); | |
558 | /* | |
559 | * We dont care about collisions. Nodes with | |
560 | * the same key stay together. | |
561 | */ | |
2bd2d6f2 | 562 | if (entity_before(se, entry)) { |
bf0f6f24 IM |
563 | link = &parent->rb_left; |
564 | } else { | |
565 | link = &parent->rb_right; | |
566 | leftmost = 0; | |
567 | } | |
568 | } | |
569 | ||
570 | /* | |
571 | * Maintain a cache of leftmost tree entries (it is frequently | |
572 | * used): | |
573 | */ | |
1af5f730 | 574 | if (leftmost) |
57cb499d | 575 | cfs_rq->rb_leftmost = &se->run_node; |
bf0f6f24 IM |
576 | |
577 | rb_link_node(&se->run_node, parent, link); | |
578 | rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline); | |
bf0f6f24 IM |
579 | } |
580 | ||
0702e3eb | 581 | static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 582 | { |
3fe69747 PZ |
583 | if (cfs_rq->rb_leftmost == &se->run_node) { |
584 | struct rb_node *next_node; | |
3fe69747 PZ |
585 | |
586 | next_node = rb_next(&se->run_node); | |
587 | cfs_rq->rb_leftmost = next_node; | |
3fe69747 | 588 | } |
e9acbff6 | 589 | |
bf0f6f24 | 590 | rb_erase(&se->run_node, &cfs_rq->tasks_timeline); |
bf0f6f24 IM |
591 | } |
592 | ||
029632fb | 593 | struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq) |
bf0f6f24 | 594 | { |
f4b6755f PZ |
595 | struct rb_node *left = cfs_rq->rb_leftmost; |
596 | ||
597 | if (!left) | |
598 | return NULL; | |
599 | ||
600 | return rb_entry(left, struct sched_entity, run_node); | |
bf0f6f24 IM |
601 | } |
602 | ||
ac53db59 RR |
603 | static struct sched_entity *__pick_next_entity(struct sched_entity *se) |
604 | { | |
605 | struct rb_node *next = rb_next(&se->run_node); | |
606 | ||
607 | if (!next) | |
608 | return NULL; | |
609 | ||
610 | return rb_entry(next, struct sched_entity, run_node); | |
611 | } | |
612 | ||
613 | #ifdef CONFIG_SCHED_DEBUG | |
029632fb | 614 | struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) |
aeb73b04 | 615 | { |
7eee3e67 | 616 | struct rb_node *last = rb_last(&cfs_rq->tasks_timeline); |
aeb73b04 | 617 | |
70eee74b BS |
618 | if (!last) |
619 | return NULL; | |
7eee3e67 IM |
620 | |
621 | return rb_entry(last, struct sched_entity, run_node); | |
aeb73b04 PZ |
622 | } |
623 | ||
bf0f6f24 IM |
624 | /************************************************************** |
625 | * Scheduling class statistics methods: | |
626 | */ | |
627 | ||
acb4a848 | 628 | int sched_proc_update_handler(struct ctl_table *table, int write, |
8d65af78 | 629 | void __user *buffer, size_t *lenp, |
b2be5e96 PZ |
630 | loff_t *ppos) |
631 | { | |
8d65af78 | 632 | int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
58ac93e4 | 633 | unsigned int factor = get_update_sysctl_factor(); |
b2be5e96 PZ |
634 | |
635 | if (ret || !write) | |
636 | return ret; | |
637 | ||
638 | sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, | |
639 | sysctl_sched_min_granularity); | |
640 | ||
acb4a848 CE |
641 | #define WRT_SYSCTL(name) \ |
642 | (normalized_sysctl_##name = sysctl_##name / (factor)) | |
643 | WRT_SYSCTL(sched_min_granularity); | |
644 | WRT_SYSCTL(sched_latency); | |
645 | WRT_SYSCTL(sched_wakeup_granularity); | |
acb4a848 CE |
646 | #undef WRT_SYSCTL |
647 | ||
b2be5e96 PZ |
648 | return 0; |
649 | } | |
650 | #endif | |
647e7cac | 651 | |
a7be37ac | 652 | /* |
f9c0b095 | 653 | * delta /= w |
a7be37ac | 654 | */ |
9dbdb155 | 655 | static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se) |
a7be37ac | 656 | { |
f9c0b095 | 657 | if (unlikely(se->load.weight != NICE_0_LOAD)) |
9dbdb155 | 658 | delta = __calc_delta(delta, NICE_0_LOAD, &se->load); |
a7be37ac PZ |
659 | |
660 | return delta; | |
661 | } | |
662 | ||
647e7cac IM |
663 | /* |
664 | * The idea is to set a period in which each task runs once. | |
665 | * | |
532b1858 | 666 | * When there are too many tasks (sched_nr_latency) we have to stretch |
647e7cac IM |
667 | * this period because otherwise the slices get too small. |
668 | * | |
669 | * p = (nr <= nl) ? l : l*nr/nl | |
670 | */ | |
4d78e7b6 PZ |
671 | static u64 __sched_period(unsigned long nr_running) |
672 | { | |
8e2b0bf3 BF |
673 | if (unlikely(nr_running > sched_nr_latency)) |
674 | return nr_running * sysctl_sched_min_granularity; | |
675 | else | |
676 | return sysctl_sched_latency; | |
4d78e7b6 PZ |
677 | } |
678 | ||
647e7cac IM |
679 | /* |
680 | * We calculate the wall-time slice from the period by taking a part | |
681 | * proportional to the weight. | |
682 | * | |
f9c0b095 | 683 | * s = p*P[w/rw] |
647e7cac | 684 | */ |
6d0f0ebd | 685 | static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
21805085 | 686 | { |
0a582440 | 687 | u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq); |
f9c0b095 | 688 | |
0a582440 | 689 | for_each_sched_entity(se) { |
6272d68c | 690 | struct load_weight *load; |
3104bf03 | 691 | struct load_weight lw; |
6272d68c LM |
692 | |
693 | cfs_rq = cfs_rq_of(se); | |
694 | load = &cfs_rq->load; | |
f9c0b095 | 695 | |
0a582440 | 696 | if (unlikely(!se->on_rq)) { |
3104bf03 | 697 | lw = cfs_rq->load; |
0a582440 MG |
698 | |
699 | update_load_add(&lw, se->load.weight); | |
700 | load = &lw; | |
701 | } | |
9dbdb155 | 702 | slice = __calc_delta(slice, se->load.weight, load); |
0a582440 MG |
703 | } |
704 | return slice; | |
bf0f6f24 IM |
705 | } |
706 | ||
647e7cac | 707 | /* |
660cc00f | 708 | * We calculate the vruntime slice of a to-be-inserted task. |
647e7cac | 709 | * |
f9c0b095 | 710 | * vs = s/w |
647e7cac | 711 | */ |
f9c0b095 | 712 | static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
67e9fb2a | 713 | { |
f9c0b095 | 714 | return calc_delta_fair(sched_slice(cfs_rq, se), se); |
a7be37ac PZ |
715 | } |
716 | ||
a75cdaa9 | 717 | #ifdef CONFIG_SMP |
772bd008 | 718 | static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu); |
fb13c7ee MG |
719 | static unsigned long task_h_load(struct task_struct *p); |
720 | ||
9d89c257 YD |
721 | /* |
722 | * We choose a half-life close to 1 scheduling period. | |
84fb5a18 LY |
723 | * Note: The tables runnable_avg_yN_inv and runnable_avg_yN_sum are |
724 | * dependent on this value. | |
9d89c257 YD |
725 | */ |
726 | #define LOAD_AVG_PERIOD 32 | |
727 | #define LOAD_AVG_MAX 47742 /* maximum possible load avg */ | |
84fb5a18 | 728 | #define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_AVG_MAX */ |
a75cdaa9 | 729 | |
540247fb YD |
730 | /* Give new sched_entity start runnable values to heavy its load in infant time */ |
731 | void init_entity_runnable_average(struct sched_entity *se) | |
a75cdaa9 | 732 | { |
540247fb | 733 | struct sched_avg *sa = &se->avg; |
a75cdaa9 | 734 | |
9d89c257 YD |
735 | sa->last_update_time = 0; |
736 | /* | |
737 | * sched_avg's period_contrib should be strictly less then 1024, so | |
738 | * we give it 1023 to make sure it is almost a period (1024us), and | |
739 | * will definitely be update (after enqueue). | |
740 | */ | |
741 | sa->period_contrib = 1023; | |
b5a9b340 VG |
742 | /* |
743 | * Tasks are intialized with full load to be seen as heavy tasks until | |
744 | * they get a chance to stabilize to their real load level. | |
745 | * Group entities are intialized with zero load to reflect the fact that | |
746 | * nothing has been attached to the task group yet. | |
747 | */ | |
748 | if (entity_is_task(se)) | |
749 | sa->load_avg = scale_load_down(se->load.weight); | |
9d89c257 | 750 | sa->load_sum = sa->load_avg * LOAD_AVG_MAX; |
2b8c41da YD |
751 | /* |
752 | * At this point, util_avg won't be used in select_task_rq_fair anyway | |
753 | */ | |
754 | sa->util_avg = 0; | |
755 | sa->util_sum = 0; | |
9d89c257 | 756 | /* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */ |
a75cdaa9 | 757 | } |
7ea241af | 758 | |
7dc603c9 | 759 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); |
df217913 | 760 | static void attach_entity_cfs_rq(struct sched_entity *se); |
7dc603c9 | 761 | |
2b8c41da YD |
762 | /* |
763 | * With new tasks being created, their initial util_avgs are extrapolated | |
764 | * based on the cfs_rq's current util_avg: | |
765 | * | |
766 | * util_avg = cfs_rq->util_avg / (cfs_rq->load_avg + 1) * se.load.weight | |
767 | * | |
768 | * However, in many cases, the above util_avg does not give a desired | |
769 | * value. Moreover, the sum of the util_avgs may be divergent, such | |
770 | * as when the series is a harmonic series. | |
771 | * | |
772 | * To solve this problem, we also cap the util_avg of successive tasks to | |
773 | * only 1/2 of the left utilization budget: | |
774 | * | |
775 | * util_avg_cap = (1024 - cfs_rq->avg.util_avg) / 2^n | |
776 | * | |
777 | * where n denotes the nth task. | |
778 | * | |
779 | * For example, a simplest series from the beginning would be like: | |
780 | * | |
781 | * task util_avg: 512, 256, 128, 64, 32, 16, 8, ... | |
782 | * cfs_rq util_avg: 512, 768, 896, 960, 992, 1008, 1016, ... | |
783 | * | |
784 | * Finally, that extrapolated util_avg is clamped to the cap (util_avg_cap) | |
785 | * if util_avg > util_avg_cap. | |
786 | */ | |
787 | void post_init_entity_util_avg(struct sched_entity *se) | |
788 | { | |
789 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
790 | struct sched_avg *sa = &se->avg; | |
172895e6 | 791 | long cap = (long)(SCHED_CAPACITY_SCALE - cfs_rq->avg.util_avg) / 2; |
2b8c41da YD |
792 | |
793 | if (cap > 0) { | |
794 | if (cfs_rq->avg.util_avg != 0) { | |
795 | sa->util_avg = cfs_rq->avg.util_avg * se->load.weight; | |
796 | sa->util_avg /= (cfs_rq->avg.load_avg + 1); | |
797 | ||
798 | if (sa->util_avg > cap) | |
799 | sa->util_avg = cap; | |
800 | } else { | |
801 | sa->util_avg = cap; | |
802 | } | |
803 | sa->util_sum = sa->util_avg * LOAD_AVG_MAX; | |
804 | } | |
7dc603c9 PZ |
805 | |
806 | if (entity_is_task(se)) { | |
807 | struct task_struct *p = task_of(se); | |
808 | if (p->sched_class != &fair_sched_class) { | |
809 | /* | |
810 | * For !fair tasks do: | |
811 | * | |
812 | update_cfs_rq_load_avg(now, cfs_rq, false); | |
813 | attach_entity_load_avg(cfs_rq, se); | |
814 | switched_from_fair(rq, p); | |
815 | * | |
816 | * such that the next switched_to_fair() has the | |
817 | * expected state. | |
818 | */ | |
df217913 | 819 | se->avg.last_update_time = cfs_rq_clock_task(cfs_rq); |
7dc603c9 PZ |
820 | return; |
821 | } | |
822 | } | |
823 | ||
df217913 | 824 | attach_entity_cfs_rq(se); |
2b8c41da YD |
825 | } |
826 | ||
7dc603c9 | 827 | #else /* !CONFIG_SMP */ |
540247fb | 828 | void init_entity_runnable_average(struct sched_entity *se) |
a75cdaa9 AS |
829 | { |
830 | } | |
2b8c41da YD |
831 | void post_init_entity_util_avg(struct sched_entity *se) |
832 | { | |
833 | } | |
3d30544f PZ |
834 | static void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) |
835 | { | |
836 | } | |
7dc603c9 | 837 | #endif /* CONFIG_SMP */ |
a75cdaa9 | 838 | |
bf0f6f24 | 839 | /* |
9dbdb155 | 840 | * Update the current task's runtime statistics. |
bf0f6f24 | 841 | */ |
b7cc0896 | 842 | static void update_curr(struct cfs_rq *cfs_rq) |
bf0f6f24 | 843 | { |
429d43bc | 844 | struct sched_entity *curr = cfs_rq->curr; |
78becc27 | 845 | u64 now = rq_clock_task(rq_of(cfs_rq)); |
9dbdb155 | 846 | u64 delta_exec; |
bf0f6f24 IM |
847 | |
848 | if (unlikely(!curr)) | |
849 | return; | |
850 | ||
9dbdb155 PZ |
851 | delta_exec = now - curr->exec_start; |
852 | if (unlikely((s64)delta_exec <= 0)) | |
34f28ecd | 853 | return; |
bf0f6f24 | 854 | |
8ebc91d9 | 855 | curr->exec_start = now; |
d842de87 | 856 | |
9dbdb155 PZ |
857 | schedstat_set(curr->statistics.exec_max, |
858 | max(delta_exec, curr->statistics.exec_max)); | |
859 | ||
860 | curr->sum_exec_runtime += delta_exec; | |
ae92882e | 861 | schedstat_add(cfs_rq->exec_clock, delta_exec); |
9dbdb155 PZ |
862 | |
863 | curr->vruntime += calc_delta_fair(delta_exec, curr); | |
864 | update_min_vruntime(cfs_rq); | |
865 | ||
d842de87 SV |
866 | if (entity_is_task(curr)) { |
867 | struct task_struct *curtask = task_of(curr); | |
868 | ||
f977bb49 | 869 | trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); |
d842de87 | 870 | cpuacct_charge(curtask, delta_exec); |
f06febc9 | 871 | account_group_exec_runtime(curtask, delta_exec); |
d842de87 | 872 | } |
ec12cb7f PT |
873 | |
874 | account_cfs_rq_runtime(cfs_rq, delta_exec); | |
bf0f6f24 IM |
875 | } |
876 | ||
6e998916 SG |
877 | static void update_curr_fair(struct rq *rq) |
878 | { | |
879 | update_curr(cfs_rq_of(&rq->curr->se)); | |
880 | } | |
881 | ||
bf0f6f24 | 882 | static inline void |
5870db5b | 883 | update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 884 | { |
4fa8d299 JP |
885 | u64 wait_start, prev_wait_start; |
886 | ||
887 | if (!schedstat_enabled()) | |
888 | return; | |
889 | ||
890 | wait_start = rq_clock(rq_of(cfs_rq)); | |
891 | prev_wait_start = schedstat_val(se->statistics.wait_start); | |
3ea94de1 JP |
892 | |
893 | if (entity_is_task(se) && task_on_rq_migrating(task_of(se)) && | |
4fa8d299 JP |
894 | likely(wait_start > prev_wait_start)) |
895 | wait_start -= prev_wait_start; | |
3ea94de1 | 896 | |
4fa8d299 | 897 | schedstat_set(se->statistics.wait_start, wait_start); |
bf0f6f24 IM |
898 | } |
899 | ||
4fa8d299 | 900 | static inline void |
3ea94de1 JP |
901 | update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) |
902 | { | |
903 | struct task_struct *p; | |
cb251765 MG |
904 | u64 delta; |
905 | ||
4fa8d299 JP |
906 | if (!schedstat_enabled()) |
907 | return; | |
908 | ||
909 | delta = rq_clock(rq_of(cfs_rq)) - schedstat_val(se->statistics.wait_start); | |
3ea94de1 JP |
910 | |
911 | if (entity_is_task(se)) { | |
912 | p = task_of(se); | |
913 | if (task_on_rq_migrating(p)) { | |
914 | /* | |
915 | * Preserve migrating task's wait time so wait_start | |
916 | * time stamp can be adjusted to accumulate wait time | |
917 | * prior to migration. | |
918 | */ | |
4fa8d299 | 919 | schedstat_set(se->statistics.wait_start, delta); |
3ea94de1 JP |
920 | return; |
921 | } | |
922 | trace_sched_stat_wait(p, delta); | |
923 | } | |
924 | ||
4fa8d299 JP |
925 | schedstat_set(se->statistics.wait_max, |
926 | max(schedstat_val(se->statistics.wait_max), delta)); | |
927 | schedstat_inc(se->statistics.wait_count); | |
928 | schedstat_add(se->statistics.wait_sum, delta); | |
929 | schedstat_set(se->statistics.wait_start, 0); | |
3ea94de1 | 930 | } |
3ea94de1 | 931 | |
4fa8d299 | 932 | static inline void |
1a3d027c JP |
933 | update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
934 | { | |
935 | struct task_struct *tsk = NULL; | |
4fa8d299 JP |
936 | u64 sleep_start, block_start; |
937 | ||
938 | if (!schedstat_enabled()) | |
939 | return; | |
940 | ||
941 | sleep_start = schedstat_val(se->statistics.sleep_start); | |
942 | block_start = schedstat_val(se->statistics.block_start); | |
1a3d027c JP |
943 | |
944 | if (entity_is_task(se)) | |
945 | tsk = task_of(se); | |
946 | ||
4fa8d299 JP |
947 | if (sleep_start) { |
948 | u64 delta = rq_clock(rq_of(cfs_rq)) - sleep_start; | |
1a3d027c JP |
949 | |
950 | if ((s64)delta < 0) | |
951 | delta = 0; | |
952 | ||
4fa8d299 JP |
953 | if (unlikely(delta > schedstat_val(se->statistics.sleep_max))) |
954 | schedstat_set(se->statistics.sleep_max, delta); | |
1a3d027c | 955 | |
4fa8d299 JP |
956 | schedstat_set(se->statistics.sleep_start, 0); |
957 | schedstat_add(se->statistics.sum_sleep_runtime, delta); | |
1a3d027c JP |
958 | |
959 | if (tsk) { | |
960 | account_scheduler_latency(tsk, delta >> 10, 1); | |
961 | trace_sched_stat_sleep(tsk, delta); | |
962 | } | |
963 | } | |
4fa8d299 JP |
964 | if (block_start) { |
965 | u64 delta = rq_clock(rq_of(cfs_rq)) - block_start; | |
1a3d027c JP |
966 | |
967 | if ((s64)delta < 0) | |
968 | delta = 0; | |
969 | ||
4fa8d299 JP |
970 | if (unlikely(delta > schedstat_val(se->statistics.block_max))) |
971 | schedstat_set(se->statistics.block_max, delta); | |
1a3d027c | 972 | |
4fa8d299 JP |
973 | schedstat_set(se->statistics.block_start, 0); |
974 | schedstat_add(se->statistics.sum_sleep_runtime, delta); | |
1a3d027c JP |
975 | |
976 | if (tsk) { | |
977 | if (tsk->in_iowait) { | |
4fa8d299 JP |
978 | schedstat_add(se->statistics.iowait_sum, delta); |
979 | schedstat_inc(se->statistics.iowait_count); | |
1a3d027c JP |
980 | trace_sched_stat_iowait(tsk, delta); |
981 | } | |
982 | ||
983 | trace_sched_stat_blocked(tsk, delta); | |
984 | ||
985 | /* | |
986 | * Blocking time is in units of nanosecs, so shift by | |
987 | * 20 to get a milliseconds-range estimation of the | |
988 | * amount of time that the task spent sleeping: | |
989 | */ | |
990 | if (unlikely(prof_on == SLEEP_PROFILING)) { | |
991 | profile_hits(SLEEP_PROFILING, | |
992 | (void *)get_wchan(tsk), | |
993 | delta >> 20); | |
994 | } | |
995 | account_scheduler_latency(tsk, delta >> 10, 0); | |
996 | } | |
997 | } | |
3ea94de1 | 998 | } |
3ea94de1 | 999 | |
bf0f6f24 IM |
1000 | /* |
1001 | * Task is being enqueued - update stats: | |
1002 | */ | |
cb251765 | 1003 | static inline void |
1a3d027c | 1004 | update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 1005 | { |
4fa8d299 JP |
1006 | if (!schedstat_enabled()) |
1007 | return; | |
1008 | ||
bf0f6f24 IM |
1009 | /* |
1010 | * Are we enqueueing a waiting task? (for current tasks | |
1011 | * a dequeue/enqueue event is a NOP) | |
1012 | */ | |
429d43bc | 1013 | if (se != cfs_rq->curr) |
5870db5b | 1014 | update_stats_wait_start(cfs_rq, se); |
1a3d027c JP |
1015 | |
1016 | if (flags & ENQUEUE_WAKEUP) | |
1017 | update_stats_enqueue_sleeper(cfs_rq, se); | |
bf0f6f24 IM |
1018 | } |
1019 | ||
bf0f6f24 | 1020 | static inline void |
cb251765 | 1021 | update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 1022 | { |
4fa8d299 JP |
1023 | |
1024 | if (!schedstat_enabled()) | |
1025 | return; | |
1026 | ||
bf0f6f24 IM |
1027 | /* |
1028 | * Mark the end of the wait period if dequeueing a | |
1029 | * waiting task: | |
1030 | */ | |
429d43bc | 1031 | if (se != cfs_rq->curr) |
9ef0a961 | 1032 | update_stats_wait_end(cfs_rq, se); |
cb251765 | 1033 | |
4fa8d299 JP |
1034 | if ((flags & DEQUEUE_SLEEP) && entity_is_task(se)) { |
1035 | struct task_struct *tsk = task_of(se); | |
cb251765 | 1036 | |
4fa8d299 JP |
1037 | if (tsk->state & TASK_INTERRUPTIBLE) |
1038 | schedstat_set(se->statistics.sleep_start, | |
1039 | rq_clock(rq_of(cfs_rq))); | |
1040 | if (tsk->state & TASK_UNINTERRUPTIBLE) | |
1041 | schedstat_set(se->statistics.block_start, | |
1042 | rq_clock(rq_of(cfs_rq))); | |
cb251765 | 1043 | } |
cb251765 MG |
1044 | } |
1045 | ||
bf0f6f24 IM |
1046 | /* |
1047 | * We are picking a new current task - update its stats: | |
1048 | */ | |
1049 | static inline void | |
79303e9e | 1050 | update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 IM |
1051 | { |
1052 | /* | |
1053 | * We are starting a new run period: | |
1054 | */ | |
78becc27 | 1055 | se->exec_start = rq_clock_task(rq_of(cfs_rq)); |
bf0f6f24 IM |
1056 | } |
1057 | ||
bf0f6f24 IM |
1058 | /************************************************** |
1059 | * Scheduling class queueing methods: | |
1060 | */ | |
1061 | ||
cbee9f88 PZ |
1062 | #ifdef CONFIG_NUMA_BALANCING |
1063 | /* | |
598f0ec0 MG |
1064 | * Approximate time to scan a full NUMA task in ms. The task scan period is |
1065 | * calculated based on the tasks virtual memory size and | |
1066 | * numa_balancing_scan_size. | |
cbee9f88 | 1067 | */ |
598f0ec0 MG |
1068 | unsigned int sysctl_numa_balancing_scan_period_min = 1000; |
1069 | unsigned int sysctl_numa_balancing_scan_period_max = 60000; | |
6e5fb223 PZ |
1070 | |
1071 | /* Portion of address space to scan in MB */ | |
1072 | unsigned int sysctl_numa_balancing_scan_size = 256; | |
cbee9f88 | 1073 | |
4b96a29b PZ |
1074 | /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */ |
1075 | unsigned int sysctl_numa_balancing_scan_delay = 1000; | |
1076 | ||
598f0ec0 MG |
1077 | static unsigned int task_nr_scan_windows(struct task_struct *p) |
1078 | { | |
1079 | unsigned long rss = 0; | |
1080 | unsigned long nr_scan_pages; | |
1081 | ||
1082 | /* | |
1083 | * Calculations based on RSS as non-present and empty pages are skipped | |
1084 | * by the PTE scanner and NUMA hinting faults should be trapped based | |
1085 | * on resident pages | |
1086 | */ | |
1087 | nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT); | |
1088 | rss = get_mm_rss(p->mm); | |
1089 | if (!rss) | |
1090 | rss = nr_scan_pages; | |
1091 | ||
1092 | rss = round_up(rss, nr_scan_pages); | |
1093 | return rss / nr_scan_pages; | |
1094 | } | |
1095 | ||
1096 | /* For sanitys sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */ | |
1097 | #define MAX_SCAN_WINDOW 2560 | |
1098 | ||
1099 | static unsigned int task_scan_min(struct task_struct *p) | |
1100 | { | |
316c1608 | 1101 | unsigned int scan_size = READ_ONCE(sysctl_numa_balancing_scan_size); |
598f0ec0 MG |
1102 | unsigned int scan, floor; |
1103 | unsigned int windows = 1; | |
1104 | ||
64192658 KT |
1105 | if (scan_size < MAX_SCAN_WINDOW) |
1106 | windows = MAX_SCAN_WINDOW / scan_size; | |
598f0ec0 MG |
1107 | floor = 1000 / windows; |
1108 | ||
1109 | scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p); | |
1110 | return max_t(unsigned int, floor, scan); | |
1111 | } | |
1112 | ||
1113 | static unsigned int task_scan_max(struct task_struct *p) | |
1114 | { | |
1115 | unsigned int smin = task_scan_min(p); | |
1116 | unsigned int smax; | |
1117 | ||
1118 | /* Watch for min being lower than max due to floor calculations */ | |
1119 | smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p); | |
1120 | return max(smin, smax); | |
1121 | } | |
1122 | ||
0ec8aa00 PZ |
1123 | static void account_numa_enqueue(struct rq *rq, struct task_struct *p) |
1124 | { | |
1125 | rq->nr_numa_running += (p->numa_preferred_nid != -1); | |
1126 | rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p)); | |
1127 | } | |
1128 | ||
1129 | static void account_numa_dequeue(struct rq *rq, struct task_struct *p) | |
1130 | { | |
1131 | rq->nr_numa_running -= (p->numa_preferred_nid != -1); | |
1132 | rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p)); | |
1133 | } | |
1134 | ||
8c8a743c PZ |
1135 | struct numa_group { |
1136 | atomic_t refcount; | |
1137 | ||
1138 | spinlock_t lock; /* nr_tasks, tasks */ | |
1139 | int nr_tasks; | |
e29cf08b | 1140 | pid_t gid; |
4142c3eb | 1141 | int active_nodes; |
8c8a743c PZ |
1142 | |
1143 | struct rcu_head rcu; | |
989348b5 | 1144 | unsigned long total_faults; |
4142c3eb | 1145 | unsigned long max_faults_cpu; |
7e2703e6 RR |
1146 | /* |
1147 | * Faults_cpu is used to decide whether memory should move | |
1148 | * towards the CPU. As a consequence, these stats are weighted | |
1149 | * more by CPU use than by memory faults. | |
1150 | */ | |
50ec8a40 | 1151 | unsigned long *faults_cpu; |
989348b5 | 1152 | unsigned long faults[0]; |
8c8a743c PZ |
1153 | }; |
1154 | ||
be1e4e76 RR |
1155 | /* Shared or private faults. */ |
1156 | #define NR_NUMA_HINT_FAULT_TYPES 2 | |
1157 | ||
1158 | /* Memory and CPU locality */ | |
1159 | #define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2) | |
1160 | ||
1161 | /* Averaged statistics, and temporary buffers. */ | |
1162 | #define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2) | |
1163 | ||
e29cf08b MG |
1164 | pid_t task_numa_group_id(struct task_struct *p) |
1165 | { | |
1166 | return p->numa_group ? p->numa_group->gid : 0; | |
1167 | } | |
1168 | ||
44dba3d5 IM |
1169 | /* |
1170 | * The averaged statistics, shared & private, memory & cpu, | |
1171 | * occupy the first half of the array. The second half of the | |
1172 | * array is for current counters, which are averaged into the | |
1173 | * first set by task_numa_placement. | |
1174 | */ | |
1175 | static inline int task_faults_idx(enum numa_faults_stats s, int nid, int priv) | |
ac8e895b | 1176 | { |
44dba3d5 | 1177 | return NR_NUMA_HINT_FAULT_TYPES * (s * nr_node_ids + nid) + priv; |
ac8e895b MG |
1178 | } |
1179 | ||
1180 | static inline unsigned long task_faults(struct task_struct *p, int nid) | |
1181 | { | |
44dba3d5 | 1182 | if (!p->numa_faults) |
ac8e895b MG |
1183 | return 0; |
1184 | ||
44dba3d5 IM |
1185 | return p->numa_faults[task_faults_idx(NUMA_MEM, nid, 0)] + |
1186 | p->numa_faults[task_faults_idx(NUMA_MEM, nid, 1)]; | |
ac8e895b MG |
1187 | } |
1188 | ||
83e1d2cd MG |
1189 | static inline unsigned long group_faults(struct task_struct *p, int nid) |
1190 | { | |
1191 | if (!p->numa_group) | |
1192 | return 0; | |
1193 | ||
44dba3d5 IM |
1194 | return p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 0)] + |
1195 | p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 1)]; | |
83e1d2cd MG |
1196 | } |
1197 | ||
20e07dea RR |
1198 | static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) |
1199 | { | |
44dba3d5 IM |
1200 | return group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 0)] + |
1201 | group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 1)]; | |
20e07dea RR |
1202 | } |
1203 | ||
4142c3eb RR |
1204 | /* |
1205 | * A node triggering more than 1/3 as many NUMA faults as the maximum is | |
1206 | * considered part of a numa group's pseudo-interleaving set. Migrations | |
1207 | * between these nodes are slowed down, to allow things to settle down. | |
1208 | */ | |
1209 | #define ACTIVE_NODE_FRACTION 3 | |
1210 | ||
1211 | static bool numa_is_active_node(int nid, struct numa_group *ng) | |
1212 | { | |
1213 | return group_faults_cpu(ng, nid) * ACTIVE_NODE_FRACTION > ng->max_faults_cpu; | |
1214 | } | |
1215 | ||
6c6b1193 RR |
1216 | /* Handle placement on systems where not all nodes are directly connected. */ |
1217 | static unsigned long score_nearby_nodes(struct task_struct *p, int nid, | |
1218 | int maxdist, bool task) | |
1219 | { | |
1220 | unsigned long score = 0; | |
1221 | int node; | |
1222 | ||
1223 | /* | |
1224 | * All nodes are directly connected, and the same distance | |
1225 | * from each other. No need for fancy placement algorithms. | |
1226 | */ | |
1227 | if (sched_numa_topology_type == NUMA_DIRECT) | |
1228 | return 0; | |
1229 | ||
1230 | /* | |
1231 | * This code is called for each node, introducing N^2 complexity, | |
1232 | * which should be ok given the number of nodes rarely exceeds 8. | |
1233 | */ | |
1234 | for_each_online_node(node) { | |
1235 | unsigned long faults; | |
1236 | int dist = node_distance(nid, node); | |
1237 | ||
1238 | /* | |
1239 | * The furthest away nodes in the system are not interesting | |
1240 | * for placement; nid was already counted. | |
1241 | */ | |
1242 | if (dist == sched_max_numa_distance || node == nid) | |
1243 | continue; | |
1244 | ||
1245 | /* | |
1246 | * On systems with a backplane NUMA topology, compare groups | |
1247 | * of nodes, and move tasks towards the group with the most | |
1248 | * memory accesses. When comparing two nodes at distance | |
1249 | * "hoplimit", only nodes closer by than "hoplimit" are part | |
1250 | * of each group. Skip other nodes. | |
1251 | */ | |
1252 | if (sched_numa_topology_type == NUMA_BACKPLANE && | |
1253 | dist > maxdist) | |
1254 | continue; | |
1255 | ||
1256 | /* Add up the faults from nearby nodes. */ | |
1257 | if (task) | |
1258 | faults = task_faults(p, node); | |
1259 | else | |
1260 | faults = group_faults(p, node); | |
1261 | ||
1262 | /* | |
1263 | * On systems with a glueless mesh NUMA topology, there are | |
1264 | * no fixed "groups of nodes". Instead, nodes that are not | |
1265 | * directly connected bounce traffic through intermediate | |
1266 | * nodes; a numa_group can occupy any set of nodes. | |
1267 | * The further away a node is, the less the faults count. | |
1268 | * This seems to result in good task placement. | |
1269 | */ | |
1270 | if (sched_numa_topology_type == NUMA_GLUELESS_MESH) { | |
1271 | faults *= (sched_max_numa_distance - dist); | |
1272 | faults /= (sched_max_numa_distance - LOCAL_DISTANCE); | |
1273 | } | |
1274 | ||
1275 | score += faults; | |
1276 | } | |
1277 | ||
1278 | return score; | |
1279 | } | |
1280 | ||
83e1d2cd MG |
1281 | /* |
1282 | * These return the fraction of accesses done by a particular task, or | |
1283 | * task group, on a particular numa node. The group weight is given a | |
1284 | * larger multiplier, in order to group tasks together that are almost | |
1285 | * evenly spread out between numa nodes. | |
1286 | */ | |
7bd95320 RR |
1287 | static inline unsigned long task_weight(struct task_struct *p, int nid, |
1288 | int dist) | |
83e1d2cd | 1289 | { |
7bd95320 | 1290 | unsigned long faults, total_faults; |
83e1d2cd | 1291 | |
44dba3d5 | 1292 | if (!p->numa_faults) |
83e1d2cd MG |
1293 | return 0; |
1294 | ||
1295 | total_faults = p->total_numa_faults; | |
1296 | ||
1297 | if (!total_faults) | |
1298 | return 0; | |
1299 | ||
7bd95320 | 1300 | faults = task_faults(p, nid); |
6c6b1193 RR |
1301 | faults += score_nearby_nodes(p, nid, dist, true); |
1302 | ||
7bd95320 | 1303 | return 1000 * faults / total_faults; |
83e1d2cd MG |
1304 | } |
1305 | ||
7bd95320 RR |
1306 | static inline unsigned long group_weight(struct task_struct *p, int nid, |
1307 | int dist) | |
83e1d2cd | 1308 | { |
7bd95320 RR |
1309 | unsigned long faults, total_faults; |
1310 | ||
1311 | if (!p->numa_group) | |
1312 | return 0; | |
1313 | ||
1314 | total_faults = p->numa_group->total_faults; | |
1315 | ||
1316 | if (!total_faults) | |
83e1d2cd MG |
1317 | return 0; |
1318 | ||
7bd95320 | 1319 | faults = group_faults(p, nid); |
6c6b1193 RR |
1320 | faults += score_nearby_nodes(p, nid, dist, false); |
1321 | ||
7bd95320 | 1322 | return 1000 * faults / total_faults; |
83e1d2cd MG |
1323 | } |
1324 | ||
10f39042 RR |
1325 | bool should_numa_migrate_memory(struct task_struct *p, struct page * page, |
1326 | int src_nid, int dst_cpu) | |
1327 | { | |
1328 | struct numa_group *ng = p->numa_group; | |
1329 | int dst_nid = cpu_to_node(dst_cpu); | |
1330 | int last_cpupid, this_cpupid; | |
1331 | ||
1332 | this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid); | |
1333 | ||
1334 | /* | |
1335 | * Multi-stage node selection is used in conjunction with a periodic | |
1336 | * migration fault to build a temporal task<->page relation. By using | |
1337 | * a two-stage filter we remove short/unlikely relations. | |
1338 | * | |
1339 | * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate | |
1340 | * a task's usage of a particular page (n_p) per total usage of this | |
1341 | * page (n_t) (in a given time-span) to a probability. | |
1342 | * | |
1343 | * Our periodic faults will sample this probability and getting the | |
1344 | * same result twice in a row, given these samples are fully | |
1345 | * independent, is then given by P(n)^2, provided our sample period | |
1346 | * is sufficiently short compared to the usage pattern. | |
1347 | * | |
1348 | * This quadric squishes small probabilities, making it less likely we | |
1349 | * act on an unlikely task<->page relation. | |
1350 | */ | |
1351 | last_cpupid = page_cpupid_xchg_last(page, this_cpupid); | |
1352 | if (!cpupid_pid_unset(last_cpupid) && | |
1353 | cpupid_to_nid(last_cpupid) != dst_nid) | |
1354 | return false; | |
1355 | ||
1356 | /* Always allow migrate on private faults */ | |
1357 | if (cpupid_match_pid(p, last_cpupid)) | |
1358 | return true; | |
1359 | ||
1360 | /* A shared fault, but p->numa_group has not been set up yet. */ | |
1361 | if (!ng) | |
1362 | return true; | |
1363 | ||
1364 | /* | |
4142c3eb RR |
1365 | * Destination node is much more heavily used than the source |
1366 | * node? Allow migration. | |
10f39042 | 1367 | */ |
4142c3eb RR |
1368 | if (group_faults_cpu(ng, dst_nid) > group_faults_cpu(ng, src_nid) * |
1369 | ACTIVE_NODE_FRACTION) | |
10f39042 RR |
1370 | return true; |
1371 | ||
1372 | /* | |
4142c3eb RR |
1373 | * Distribute memory according to CPU & memory use on each node, |
1374 | * with 3/4 hysteresis to avoid unnecessary memory migrations: | |
1375 | * | |
1376 | * faults_cpu(dst) 3 faults_cpu(src) | |
1377 | * --------------- * - > --------------- | |
1378 | * faults_mem(dst) 4 faults_mem(src) | |
10f39042 | 1379 | */ |
4142c3eb RR |
1380 | return group_faults_cpu(ng, dst_nid) * group_faults(p, src_nid) * 3 > |
1381 | group_faults_cpu(ng, src_nid) * group_faults(p, dst_nid) * 4; | |
10f39042 RR |
1382 | } |
1383 | ||
e6628d5b | 1384 | static unsigned long weighted_cpuload(const int cpu); |
58d081b5 MG |
1385 | static unsigned long source_load(int cpu, int type); |
1386 | static unsigned long target_load(int cpu, int type); | |
ced549fa | 1387 | static unsigned long capacity_of(int cpu); |
58d081b5 MG |
1388 | static long effective_load(struct task_group *tg, int cpu, long wl, long wg); |
1389 | ||
fb13c7ee | 1390 | /* Cached statistics for all CPUs within a node */ |
58d081b5 | 1391 | struct numa_stats { |
fb13c7ee | 1392 | unsigned long nr_running; |
58d081b5 | 1393 | unsigned long load; |
fb13c7ee MG |
1394 | |
1395 | /* Total compute capacity of CPUs on a node */ | |
5ef20ca1 | 1396 | unsigned long compute_capacity; |
fb13c7ee MG |
1397 | |
1398 | /* Approximate capacity in terms of runnable tasks on a node */ | |
5ef20ca1 | 1399 | unsigned long task_capacity; |
1b6a7495 | 1400 | int has_free_capacity; |
58d081b5 | 1401 | }; |
e6628d5b | 1402 | |
fb13c7ee MG |
1403 | /* |
1404 | * XXX borrowed from update_sg_lb_stats | |
1405 | */ | |
1406 | static void update_numa_stats(struct numa_stats *ns, int nid) | |
1407 | { | |
83d7f242 RR |
1408 | int smt, cpu, cpus = 0; |
1409 | unsigned long capacity; | |
fb13c7ee MG |
1410 | |
1411 | memset(ns, 0, sizeof(*ns)); | |
1412 | for_each_cpu(cpu, cpumask_of_node(nid)) { | |
1413 | struct rq *rq = cpu_rq(cpu); | |
1414 | ||
1415 | ns->nr_running += rq->nr_running; | |
1416 | ns->load += weighted_cpuload(cpu); | |
ced549fa | 1417 | ns->compute_capacity += capacity_of(cpu); |
5eca82a9 PZ |
1418 | |
1419 | cpus++; | |
fb13c7ee MG |
1420 | } |
1421 | ||
5eca82a9 PZ |
1422 | /* |
1423 | * If we raced with hotplug and there are no CPUs left in our mask | |
1424 | * the @ns structure is NULL'ed and task_numa_compare() will | |
1425 | * not find this node attractive. | |
1426 | * | |
1b6a7495 NP |
1427 | * We'll either bail at !has_free_capacity, or we'll detect a huge |
1428 | * imbalance and bail there. | |
5eca82a9 PZ |
1429 | */ |
1430 | if (!cpus) | |
1431 | return; | |
1432 | ||
83d7f242 RR |
1433 | /* smt := ceil(cpus / capacity), assumes: 1 < smt_power < 2 */ |
1434 | smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, ns->compute_capacity); | |
1435 | capacity = cpus / smt; /* cores */ | |
1436 | ||
1437 | ns->task_capacity = min_t(unsigned, capacity, | |
1438 | DIV_ROUND_CLOSEST(ns->compute_capacity, SCHED_CAPACITY_SCALE)); | |
1b6a7495 | 1439 | ns->has_free_capacity = (ns->nr_running < ns->task_capacity); |
fb13c7ee MG |
1440 | } |
1441 | ||
58d081b5 MG |
1442 | struct task_numa_env { |
1443 | struct task_struct *p; | |
e6628d5b | 1444 | |
58d081b5 MG |
1445 | int src_cpu, src_nid; |
1446 | int dst_cpu, dst_nid; | |
e6628d5b | 1447 | |
58d081b5 | 1448 | struct numa_stats src_stats, dst_stats; |
e6628d5b | 1449 | |
40ea2b42 | 1450 | int imbalance_pct; |
7bd95320 | 1451 | int dist; |
fb13c7ee MG |
1452 | |
1453 | struct task_struct *best_task; | |
1454 | long best_imp; | |
58d081b5 MG |
1455 | int best_cpu; |
1456 | }; | |
1457 | ||
fb13c7ee MG |
1458 | static void task_numa_assign(struct task_numa_env *env, |
1459 | struct task_struct *p, long imp) | |
1460 | { | |
1461 | if (env->best_task) | |
1462 | put_task_struct(env->best_task); | |
bac78573 ON |
1463 | if (p) |
1464 | get_task_struct(p); | |
fb13c7ee MG |
1465 | |
1466 | env->best_task = p; | |
1467 | env->best_imp = imp; | |
1468 | env->best_cpu = env->dst_cpu; | |
1469 | } | |
1470 | ||
28a21745 | 1471 | static bool load_too_imbalanced(long src_load, long dst_load, |
e63da036 RR |
1472 | struct task_numa_env *env) |
1473 | { | |
e4991b24 RR |
1474 | long imb, old_imb; |
1475 | long orig_src_load, orig_dst_load; | |
28a21745 RR |
1476 | long src_capacity, dst_capacity; |
1477 | ||
1478 | /* | |
1479 | * The load is corrected for the CPU capacity available on each node. | |
1480 | * | |
1481 | * src_load dst_load | |
1482 | * ------------ vs --------- | |
1483 | * src_capacity dst_capacity | |
1484 | */ | |
1485 | src_capacity = env->src_stats.compute_capacity; | |
1486 | dst_capacity = env->dst_stats.compute_capacity; | |
e63da036 RR |
1487 | |
1488 | /* We care about the slope of the imbalance, not the direction. */ | |
e4991b24 RR |
1489 | if (dst_load < src_load) |
1490 | swap(dst_load, src_load); | |
e63da036 RR |
1491 | |
1492 | /* Is the difference below the threshold? */ | |
e4991b24 RR |
1493 | imb = dst_load * src_capacity * 100 - |
1494 | src_load * dst_capacity * env->imbalance_pct; | |
e63da036 RR |
1495 | if (imb <= 0) |
1496 | return false; | |
1497 | ||
1498 | /* | |
1499 | * The imbalance is above the allowed threshold. | |
e4991b24 | 1500 | * Compare it with the old imbalance. |
e63da036 | 1501 | */ |
28a21745 | 1502 | orig_src_load = env->src_stats.load; |
e4991b24 | 1503 | orig_dst_load = env->dst_stats.load; |
28a21745 | 1504 | |
e4991b24 RR |
1505 | if (orig_dst_load < orig_src_load) |
1506 | swap(orig_dst_load, orig_src_load); | |
e63da036 | 1507 | |
e4991b24 RR |
1508 | old_imb = orig_dst_load * src_capacity * 100 - |
1509 | orig_src_load * dst_capacity * env->imbalance_pct; | |
1510 | ||
1511 | /* Would this change make things worse? */ | |
1512 | return (imb > old_imb); | |
e63da036 RR |
1513 | } |
1514 | ||
fb13c7ee MG |
1515 | /* |
1516 | * This checks if the overall compute and NUMA accesses of the system would | |
1517 | * be improved if the source tasks was migrated to the target dst_cpu taking | |
1518 | * into account that it might be best if task running on the dst_cpu should | |
1519 | * be exchanged with the source task | |
1520 | */ | |
887c290e RR |
1521 | static void task_numa_compare(struct task_numa_env *env, |
1522 | long taskimp, long groupimp) | |
fb13c7ee MG |
1523 | { |
1524 | struct rq *src_rq = cpu_rq(env->src_cpu); | |
1525 | struct rq *dst_rq = cpu_rq(env->dst_cpu); | |
1526 | struct task_struct *cur; | |
28a21745 | 1527 | long src_load, dst_load; |
fb13c7ee | 1528 | long load; |
1c5d3eb3 | 1529 | long imp = env->p->numa_group ? groupimp : taskimp; |
0132c3e1 | 1530 | long moveimp = imp; |
7bd95320 | 1531 | int dist = env->dist; |
fb13c7ee MG |
1532 | |
1533 | rcu_read_lock(); | |
bac78573 ON |
1534 | cur = task_rcu_dereference(&dst_rq->curr); |
1535 | if (cur && ((cur->flags & PF_EXITING) || is_idle_task(cur))) | |
fb13c7ee MG |
1536 | cur = NULL; |
1537 | ||
7af68335 PZ |
1538 | /* |
1539 | * Because we have preemption enabled we can get migrated around and | |
1540 | * end try selecting ourselves (current == env->p) as a swap candidate. | |
1541 | */ | |
1542 | if (cur == env->p) | |
1543 | goto unlock; | |
1544 | ||
fb13c7ee MG |
1545 | /* |
1546 | * "imp" is the fault differential for the source task between the | |
1547 | * source and destination node. Calculate the total differential for | |
1548 | * the source task and potential destination task. The more negative | |
1549 | * the value is, the more rmeote accesses that would be expected to | |
1550 | * be incurred if the tasks were swapped. | |
1551 | */ | |
1552 | if (cur) { | |
1553 | /* Skip this swap candidate if cannot move to the source cpu */ | |
1554 | if (!cpumask_test_cpu(env->src_cpu, tsk_cpus_allowed(cur))) | |
1555 | goto unlock; | |
1556 | ||
887c290e RR |
1557 | /* |
1558 | * If dst and source tasks are in the same NUMA group, or not | |
ca28aa53 | 1559 | * in any group then look only at task weights. |
887c290e | 1560 | */ |
ca28aa53 | 1561 | if (cur->numa_group == env->p->numa_group) { |
7bd95320 RR |
1562 | imp = taskimp + task_weight(cur, env->src_nid, dist) - |
1563 | task_weight(cur, env->dst_nid, dist); | |
ca28aa53 RR |
1564 | /* |
1565 | * Add some hysteresis to prevent swapping the | |
1566 | * tasks within a group over tiny differences. | |
1567 | */ | |
1568 | if (cur->numa_group) | |
1569 | imp -= imp/16; | |
887c290e | 1570 | } else { |
ca28aa53 RR |
1571 | /* |
1572 | * Compare the group weights. If a task is all by | |
1573 | * itself (not part of a group), use the task weight | |
1574 | * instead. | |
1575 | */ | |
ca28aa53 | 1576 | if (cur->numa_group) |
7bd95320 RR |
1577 | imp += group_weight(cur, env->src_nid, dist) - |
1578 | group_weight(cur, env->dst_nid, dist); | |
ca28aa53 | 1579 | else |
7bd95320 RR |
1580 | imp += task_weight(cur, env->src_nid, dist) - |
1581 | task_weight(cur, env->dst_nid, dist); | |
887c290e | 1582 | } |
fb13c7ee MG |
1583 | } |
1584 | ||
0132c3e1 | 1585 | if (imp <= env->best_imp && moveimp <= env->best_imp) |
fb13c7ee MG |
1586 | goto unlock; |
1587 | ||
1588 | if (!cur) { | |
1589 | /* Is there capacity at our destination? */ | |
b932c03c | 1590 | if (env->src_stats.nr_running <= env->src_stats.task_capacity && |
1b6a7495 | 1591 | !env->dst_stats.has_free_capacity) |
fb13c7ee MG |
1592 | goto unlock; |
1593 | ||
1594 | goto balance; | |
1595 | } | |
1596 | ||
1597 | /* Balance doesn't matter much if we're running a task per cpu */ | |
0132c3e1 RR |
1598 | if (imp > env->best_imp && src_rq->nr_running == 1 && |
1599 | dst_rq->nr_running == 1) | |
fb13c7ee MG |
1600 | goto assign; |
1601 | ||
1602 | /* | |
1603 | * In the overloaded case, try and keep the load balanced. | |
1604 | */ | |
1605 | balance: | |
e720fff6 PZ |
1606 | load = task_h_load(env->p); |
1607 | dst_load = env->dst_stats.load + load; | |
1608 | src_load = env->src_stats.load - load; | |
fb13c7ee | 1609 | |
0132c3e1 RR |
1610 | if (moveimp > imp && moveimp > env->best_imp) { |
1611 | /* | |
1612 | * If the improvement from just moving env->p direction is | |
1613 | * better than swapping tasks around, check if a move is | |
1614 | * possible. Store a slightly smaller score than moveimp, | |
1615 | * so an actually idle CPU will win. | |
1616 | */ | |
1617 | if (!load_too_imbalanced(src_load, dst_load, env)) { | |
1618 | imp = moveimp - 1; | |
1619 | cur = NULL; | |
1620 | goto assign; | |
1621 | } | |
1622 | } | |
1623 | ||
1624 | if (imp <= env->best_imp) | |
1625 | goto unlock; | |
1626 | ||
fb13c7ee | 1627 | if (cur) { |
e720fff6 PZ |
1628 | load = task_h_load(cur); |
1629 | dst_load -= load; | |
1630 | src_load += load; | |
fb13c7ee MG |
1631 | } |
1632 | ||
28a21745 | 1633 | if (load_too_imbalanced(src_load, dst_load, env)) |
fb13c7ee MG |
1634 | goto unlock; |
1635 | ||
ba7e5a27 RR |
1636 | /* |
1637 | * One idle CPU per node is evaluated for a task numa move. | |
1638 | * Call select_idle_sibling to maybe find a better one. | |
1639 | */ | |
10e2f1ac PZ |
1640 | if (!cur) { |
1641 | /* | |
1642 | * select_idle_siblings() uses an per-cpu cpumask that | |
1643 | * can be used from IRQ context. | |
1644 | */ | |
1645 | local_irq_disable(); | |
772bd008 MR |
1646 | env->dst_cpu = select_idle_sibling(env->p, env->src_cpu, |
1647 | env->dst_cpu); | |
10e2f1ac PZ |
1648 | local_irq_enable(); |
1649 | } | |
ba7e5a27 | 1650 | |
fb13c7ee MG |
1651 | assign: |
1652 | task_numa_assign(env, cur, imp); | |
1653 | unlock: | |
1654 | rcu_read_unlock(); | |
1655 | } | |
1656 | ||
887c290e RR |
1657 | static void task_numa_find_cpu(struct task_numa_env *env, |
1658 | long taskimp, long groupimp) | |
2c8a50aa MG |
1659 | { |
1660 | int cpu; | |
1661 | ||
1662 | for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) { | |
1663 | /* Skip this CPU if the source task cannot migrate */ | |
1664 | if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p))) | |
1665 | continue; | |
1666 | ||
1667 | env->dst_cpu = cpu; | |
887c290e | 1668 | task_numa_compare(env, taskimp, groupimp); |
2c8a50aa MG |
1669 | } |
1670 | } | |
1671 | ||
6f9aad0b RR |
1672 | /* Only move tasks to a NUMA node less busy than the current node. */ |
1673 | static bool numa_has_capacity(struct task_numa_env *env) | |
1674 | { | |
1675 | struct numa_stats *src = &env->src_stats; | |
1676 | struct numa_stats *dst = &env->dst_stats; | |
1677 | ||
1678 | if (src->has_free_capacity && !dst->has_free_capacity) | |
1679 | return false; | |
1680 | ||
1681 | /* | |
1682 | * Only consider a task move if the source has a higher load | |
1683 | * than the destination, corrected for CPU capacity on each node. | |
1684 | * | |
1685 | * src->load dst->load | |
1686 | * --------------------- vs --------------------- | |
1687 | * src->compute_capacity dst->compute_capacity | |
1688 | */ | |
44dcb04f SD |
1689 | if (src->load * dst->compute_capacity * env->imbalance_pct > |
1690 | ||
1691 | dst->load * src->compute_capacity * 100) | |
6f9aad0b RR |
1692 | return true; |
1693 | ||
1694 | return false; | |
1695 | } | |
1696 | ||
58d081b5 MG |
1697 | static int task_numa_migrate(struct task_struct *p) |
1698 | { | |
58d081b5 MG |
1699 | struct task_numa_env env = { |
1700 | .p = p, | |
fb13c7ee | 1701 | |
58d081b5 | 1702 | .src_cpu = task_cpu(p), |
b32e86b4 | 1703 | .src_nid = task_node(p), |
fb13c7ee MG |
1704 | |
1705 | .imbalance_pct = 112, | |
1706 | ||
1707 | .best_task = NULL, | |
1708 | .best_imp = 0, | |
4142c3eb | 1709 | .best_cpu = -1, |
58d081b5 MG |
1710 | }; |
1711 | struct sched_domain *sd; | |
887c290e | 1712 | unsigned long taskweight, groupweight; |
7bd95320 | 1713 | int nid, ret, dist; |
887c290e | 1714 | long taskimp, groupimp; |
e6628d5b | 1715 | |
58d081b5 | 1716 | /* |
fb13c7ee MG |
1717 | * Pick the lowest SD_NUMA domain, as that would have the smallest |
1718 | * imbalance and would be the first to start moving tasks about. | |
1719 | * | |
1720 | * And we want to avoid any moving of tasks about, as that would create | |
1721 | * random movement of tasks -- counter the numa conditions we're trying | |
1722 | * to satisfy here. | |
58d081b5 MG |
1723 | */ |
1724 | rcu_read_lock(); | |
fb13c7ee | 1725 | sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu)); |
46a73e8a RR |
1726 | if (sd) |
1727 | env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2; | |
e6628d5b MG |
1728 | rcu_read_unlock(); |
1729 | ||
46a73e8a RR |
1730 | /* |
1731 | * Cpusets can break the scheduler domain tree into smaller | |
1732 | * balance domains, some of which do not cross NUMA boundaries. | |
1733 | * Tasks that are "trapped" in such domains cannot be migrated | |
1734 | * elsewhere, so there is no point in (re)trying. | |
1735 | */ | |
1736 | if (unlikely(!sd)) { | |
de1b301a | 1737 | p->numa_preferred_nid = task_node(p); |
46a73e8a RR |
1738 | return -EINVAL; |
1739 | } | |
1740 | ||
2c8a50aa | 1741 | env.dst_nid = p->numa_preferred_nid; |
7bd95320 RR |
1742 | dist = env.dist = node_distance(env.src_nid, env.dst_nid); |
1743 | taskweight = task_weight(p, env.src_nid, dist); | |
1744 | groupweight = group_weight(p, env.src_nid, dist); | |
1745 | update_numa_stats(&env.src_stats, env.src_nid); | |
1746 | taskimp = task_weight(p, env.dst_nid, dist) - taskweight; | |
1747 | groupimp = group_weight(p, env.dst_nid, dist) - groupweight; | |
2c8a50aa | 1748 | update_numa_stats(&env.dst_stats, env.dst_nid); |
58d081b5 | 1749 | |
a43455a1 | 1750 | /* Try to find a spot on the preferred nid. */ |
6f9aad0b RR |
1751 | if (numa_has_capacity(&env)) |
1752 | task_numa_find_cpu(&env, taskimp, groupimp); | |
e1dda8a7 | 1753 | |
9de05d48 RR |
1754 | /* |
1755 | * Look at other nodes in these cases: | |
1756 | * - there is no space available on the preferred_nid | |
1757 | * - the task is part of a numa_group that is interleaved across | |
1758 | * multiple NUMA nodes; in order to better consolidate the group, | |
1759 | * we need to check other locations. | |
1760 | */ | |
4142c3eb | 1761 | if (env.best_cpu == -1 || (p->numa_group && p->numa_group->active_nodes > 1)) { |
2c8a50aa MG |
1762 | for_each_online_node(nid) { |
1763 | if (nid == env.src_nid || nid == p->numa_preferred_nid) | |
1764 | continue; | |
58d081b5 | 1765 | |
7bd95320 | 1766 | dist = node_distance(env.src_nid, env.dst_nid); |
6c6b1193 RR |
1767 | if (sched_numa_topology_type == NUMA_BACKPLANE && |
1768 | dist != env.dist) { | |
1769 | taskweight = task_weight(p, env.src_nid, dist); | |
1770 | groupweight = group_weight(p, env.src_nid, dist); | |
1771 | } | |
7bd95320 | 1772 | |
83e1d2cd | 1773 | /* Only consider nodes where both task and groups benefit */ |
7bd95320 RR |
1774 | taskimp = task_weight(p, nid, dist) - taskweight; |
1775 | groupimp = group_weight(p, nid, dist) - groupweight; | |
887c290e | 1776 | if (taskimp < 0 && groupimp < 0) |
fb13c7ee MG |
1777 | continue; |
1778 | ||
7bd95320 | 1779 | env.dist = dist; |
2c8a50aa MG |
1780 | env.dst_nid = nid; |
1781 | update_numa_stats(&env.dst_stats, env.dst_nid); | |
6f9aad0b RR |
1782 | if (numa_has_capacity(&env)) |
1783 | task_numa_find_cpu(&env, taskimp, groupimp); | |
58d081b5 MG |
1784 | } |
1785 | } | |
1786 | ||
68d1b02a RR |
1787 | /* |
1788 | * If the task is part of a workload that spans multiple NUMA nodes, | |
1789 | * and is migrating into one of the workload's active nodes, remember | |
1790 | * this node as the task's preferred numa node, so the workload can | |
1791 | * settle down. | |
1792 | * A task that migrated to a second choice node will be better off | |
1793 | * trying for a better one later. Do not set the preferred node here. | |
1794 | */ | |
db015dae | 1795 | if (p->numa_group) { |
4142c3eb RR |
1796 | struct numa_group *ng = p->numa_group; |
1797 | ||
db015dae RR |
1798 | if (env.best_cpu == -1) |
1799 | nid = env.src_nid; | |
1800 | else | |
1801 | nid = env.dst_nid; | |
1802 | ||
4142c3eb | 1803 | if (ng->active_nodes > 1 && numa_is_active_node(env.dst_nid, ng)) |
db015dae RR |
1804 | sched_setnuma(p, env.dst_nid); |
1805 | } | |
1806 | ||
1807 | /* No better CPU than the current one was found. */ | |
1808 | if (env.best_cpu == -1) | |
1809 | return -EAGAIN; | |
0ec8aa00 | 1810 | |
04bb2f94 RR |
1811 | /* |
1812 | * Reset the scan period if the task is being rescheduled on an | |
1813 | * alternative node to recheck if the tasks is now properly placed. | |
1814 | */ | |
1815 | p->numa_scan_period = task_scan_min(p); | |
1816 | ||
fb13c7ee | 1817 | if (env.best_task == NULL) { |
286549dc MG |
1818 | ret = migrate_task_to(p, env.best_cpu); |
1819 | if (ret != 0) | |
1820 | trace_sched_stick_numa(p, env.src_cpu, env.best_cpu); | |
fb13c7ee MG |
1821 | return ret; |
1822 | } | |
1823 | ||
1824 | ret = migrate_swap(p, env.best_task); | |
286549dc MG |
1825 | if (ret != 0) |
1826 | trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task)); | |
fb13c7ee MG |
1827 | put_task_struct(env.best_task); |
1828 | return ret; | |
e6628d5b MG |
1829 | } |
1830 | ||
6b9a7460 MG |
1831 | /* Attempt to migrate a task to a CPU on the preferred node. */ |
1832 | static void numa_migrate_preferred(struct task_struct *p) | |
1833 | { | |
5085e2a3 RR |
1834 | unsigned long interval = HZ; |
1835 | ||
2739d3ee | 1836 | /* This task has no NUMA fault statistics yet */ |
44dba3d5 | 1837 | if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults)) |
6b9a7460 MG |
1838 | return; |
1839 | ||
2739d3ee | 1840 | /* Periodically retry migrating the task to the preferred node */ |
5085e2a3 RR |
1841 | interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16); |
1842 | p->numa_migrate_retry = jiffies + interval; | |
2739d3ee RR |
1843 | |
1844 | /* Success if task is already running on preferred CPU */ | |
de1b301a | 1845 | if (task_node(p) == p->numa_preferred_nid) |
6b9a7460 MG |
1846 | return; |
1847 | ||
1848 | /* Otherwise, try migrate to a CPU on the preferred node */ | |
2739d3ee | 1849 | task_numa_migrate(p); |
6b9a7460 MG |
1850 | } |
1851 | ||
20e07dea | 1852 | /* |
4142c3eb | 1853 | * Find out how many nodes on the workload is actively running on. Do this by |
20e07dea RR |
1854 | * tracking the nodes from which NUMA hinting faults are triggered. This can |
1855 | * be different from the set of nodes where the workload's memory is currently | |
1856 | * located. | |
20e07dea | 1857 | */ |
4142c3eb | 1858 | static void numa_group_count_active_nodes(struct numa_group *numa_group) |
20e07dea RR |
1859 | { |
1860 | unsigned long faults, max_faults = 0; | |
4142c3eb | 1861 | int nid, active_nodes = 0; |
20e07dea RR |
1862 | |
1863 | for_each_online_node(nid) { | |
1864 | faults = group_faults_cpu(numa_group, nid); | |
1865 | if (faults > max_faults) | |
1866 | max_faults = faults; | |
1867 | } | |
1868 | ||
1869 | for_each_online_node(nid) { | |
1870 | faults = group_faults_cpu(numa_group, nid); | |
4142c3eb RR |
1871 | if (faults * ACTIVE_NODE_FRACTION > max_faults) |
1872 | active_nodes++; | |
20e07dea | 1873 | } |
4142c3eb RR |
1874 | |
1875 | numa_group->max_faults_cpu = max_faults; | |
1876 | numa_group->active_nodes = active_nodes; | |
20e07dea RR |
1877 | } |
1878 | ||
04bb2f94 RR |
1879 | /* |
1880 | * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS | |
1881 | * increments. The more local the fault statistics are, the higher the scan | |
a22b4b01 RR |
1882 | * period will be for the next scan window. If local/(local+remote) ratio is |
1883 | * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS) | |
1884 | * the scan period will decrease. Aim for 70% local accesses. | |
04bb2f94 RR |
1885 | */ |
1886 | #define NUMA_PERIOD_SLOTS 10 | |
a22b4b01 | 1887 | #define NUMA_PERIOD_THRESHOLD 7 |
04bb2f94 RR |
1888 | |
1889 | /* | |
1890 | * Increase the scan period (slow down scanning) if the majority of | |
1891 | * our memory is already on our local node, or if the majority of | |
1892 | * the page accesses are shared with other processes. | |
1893 | * Otherwise, decrease the scan period. | |
1894 | */ | |
1895 | static void update_task_scan_period(struct task_struct *p, | |
1896 | unsigned long shared, unsigned long private) | |
1897 | { | |
1898 | unsigned int period_slot; | |
1899 | int ratio; | |
1900 | int diff; | |
1901 | ||
1902 | unsigned long remote = p->numa_faults_locality[0]; | |
1903 | unsigned long local = p->numa_faults_locality[1]; | |
1904 | ||
1905 | /* | |
1906 | * If there were no record hinting faults then either the task is | |
1907 | * completely idle or all activity is areas that are not of interest | |
074c2381 MG |
1908 | * to automatic numa balancing. Related to that, if there were failed |
1909 | * migration then it implies we are migrating too quickly or the local | |
1910 | * node is overloaded. In either case, scan slower | |
04bb2f94 | 1911 | */ |
074c2381 | 1912 | if (local + shared == 0 || p->numa_faults_locality[2]) { |
04bb2f94 RR |
1913 | p->numa_scan_period = min(p->numa_scan_period_max, |
1914 | p->numa_scan_period << 1); | |
1915 | ||
1916 | p->mm->numa_next_scan = jiffies + | |
1917 | msecs_to_jiffies(p->numa_scan_period); | |
1918 | ||
1919 | return; | |
1920 | } | |
1921 | ||
1922 | /* | |
1923 | * Prepare to scale scan period relative to the current period. | |
1924 | * == NUMA_PERIOD_THRESHOLD scan period stays the same | |
1925 | * < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster) | |
1926 | * >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower) | |
1927 | */ | |
1928 | period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS); | |
1929 | ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote); | |
1930 | if (ratio >= NUMA_PERIOD_THRESHOLD) { | |
1931 | int slot = ratio - NUMA_PERIOD_THRESHOLD; | |
1932 | if (!slot) | |
1933 | slot = 1; | |
1934 | diff = slot * period_slot; | |
1935 | } else { | |
1936 | diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot; | |
1937 | ||
1938 | /* | |
1939 | * Scale scan rate increases based on sharing. There is an | |
1940 | * inverse relationship between the degree of sharing and | |
1941 | * the adjustment made to the scanning period. Broadly | |
1942 | * speaking the intent is that there is little point | |
1943 | * scanning faster if shared accesses dominate as it may | |
1944 | * simply bounce migrations uselessly | |
1945 | */ | |
2847c90e | 1946 | ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared + 1)); |
04bb2f94 RR |
1947 | diff = (diff * ratio) / NUMA_PERIOD_SLOTS; |
1948 | } | |
1949 | ||
1950 | p->numa_scan_period = clamp(p->numa_scan_period + diff, | |
1951 | task_scan_min(p), task_scan_max(p)); | |
1952 | memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); | |
1953 | } | |
1954 | ||
7e2703e6 RR |
1955 | /* |
1956 | * Get the fraction of time the task has been running since the last | |
1957 | * NUMA placement cycle. The scheduler keeps similar statistics, but | |
1958 | * decays those on a 32ms period, which is orders of magnitude off | |
1959 | * from the dozens-of-seconds NUMA balancing period. Use the scheduler | |
1960 | * stats only if the task is so new there are no NUMA statistics yet. | |
1961 | */ | |
1962 | static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period) | |
1963 | { | |
1964 | u64 runtime, delta, now; | |
1965 | /* Use the start of this time slice to avoid calculations. */ | |
1966 | now = p->se.exec_start; | |
1967 | runtime = p->se.sum_exec_runtime; | |
1968 | ||
1969 | if (p->last_task_numa_placement) { | |
1970 | delta = runtime - p->last_sum_exec_runtime; | |
1971 | *period = now - p->last_task_numa_placement; | |
1972 | } else { | |
9d89c257 YD |
1973 | delta = p->se.avg.load_sum / p->se.load.weight; |
1974 | *period = LOAD_AVG_MAX; | |
7e2703e6 RR |
1975 | } |
1976 | ||
1977 | p->last_sum_exec_runtime = runtime; | |
1978 | p->last_task_numa_placement = now; | |
1979 | ||
1980 | return delta; | |
1981 | } | |
1982 | ||
54009416 RR |
1983 | /* |
1984 | * Determine the preferred nid for a task in a numa_group. This needs to | |
1985 | * be done in a way that produces consistent results with group_weight, | |
1986 | * otherwise workloads might not converge. | |
1987 | */ | |
1988 | static int preferred_group_nid(struct task_struct *p, int nid) | |
1989 | { | |
1990 | nodemask_t nodes; | |
1991 | int dist; | |
1992 | ||
1993 | /* Direct connections between all NUMA nodes. */ | |
1994 | if (sched_numa_topology_type == NUMA_DIRECT) | |
1995 | return nid; | |
1996 | ||
1997 | /* | |
1998 | * On a system with glueless mesh NUMA topology, group_weight | |
1999 | * scores nodes according to the number of NUMA hinting faults on | |
2000 | * both the node itself, and on nearby nodes. | |
2001 | */ | |
2002 | if (sched_numa_topology_type == NUMA_GLUELESS_MESH) { | |
2003 | unsigned long score, max_score = 0; | |
2004 | int node, max_node = nid; | |
2005 | ||
2006 | dist = sched_max_numa_distance; | |
2007 | ||
2008 | for_each_online_node(node) { | |
2009 | score = group_weight(p, node, dist); | |
2010 | if (score > max_score) { | |
2011 | max_score = score; | |
2012 | max_node = node; | |
2013 | } | |
2014 | } | |
2015 | return max_node; | |
2016 | } | |
2017 | ||
2018 | /* | |
2019 | * Finding the preferred nid in a system with NUMA backplane | |
2020 | * interconnect topology is more involved. The goal is to locate | |
2021 | * tasks from numa_groups near each other in the system, and | |
2022 | * untangle workloads from different sides of the system. This requires | |
2023 | * searching down the hierarchy of node groups, recursively searching | |
2024 | * inside the highest scoring group of nodes. The nodemask tricks | |
2025 | * keep the complexity of the search down. | |
2026 | */ | |
2027 | nodes = node_online_map; | |
2028 | for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) { | |
2029 | unsigned long max_faults = 0; | |
81907478 | 2030 | nodemask_t max_group = NODE_MASK_NONE; |
54009416 RR |
2031 | int a, b; |
2032 | ||
2033 | /* Are there nodes at this distance from each other? */ | |
2034 | if (!find_numa_distance(dist)) | |
2035 | continue; | |
2036 | ||
2037 | for_each_node_mask(a, nodes) { | |
2038 | unsigned long faults = 0; | |
2039 | nodemask_t this_group; | |
2040 | nodes_clear(this_group); | |
2041 | ||
2042 | /* Sum group's NUMA faults; includes a==b case. */ | |
2043 | for_each_node_mask(b, nodes) { | |
2044 | if (node_distance(a, b) < dist) { | |
2045 | faults += group_faults(p, b); | |
2046 | node_set(b, this_group); | |
2047 | node_clear(b, nodes); | |
2048 | } | |
2049 | } | |
2050 | ||
2051 | /* Remember the top group. */ | |
2052 | if (faults > max_faults) { | |
2053 | max_faults = faults; | |
2054 | max_group = this_group; | |
2055 | /* | |
2056 | * subtle: at the smallest distance there is | |
2057 | * just one node left in each "group", the | |
2058 | * winner is the preferred nid. | |
2059 | */ | |
2060 | nid = a; | |
2061 | } | |
2062 | } | |
2063 | /* Next round, evaluate the nodes within max_group. */ | |
890a5409 JB |
2064 | if (!max_faults) |
2065 | break; | |
54009416 RR |
2066 | nodes = max_group; |
2067 | } | |
2068 | return nid; | |
2069 | } | |
2070 | ||
cbee9f88 PZ |
2071 | static void task_numa_placement(struct task_struct *p) |
2072 | { | |
83e1d2cd MG |
2073 | int seq, nid, max_nid = -1, max_group_nid = -1; |
2074 | unsigned long max_faults = 0, max_group_faults = 0; | |
04bb2f94 | 2075 | unsigned long fault_types[2] = { 0, 0 }; |
7e2703e6 RR |
2076 | unsigned long total_faults; |
2077 | u64 runtime, period; | |
7dbd13ed | 2078 | spinlock_t *group_lock = NULL; |
cbee9f88 | 2079 | |
7e5a2c17 JL |
2080 | /* |
2081 | * The p->mm->numa_scan_seq field gets updated without | |
2082 | * exclusive access. Use READ_ONCE() here to ensure | |
2083 | * that the field is read in a single access: | |
2084 | */ | |
316c1608 | 2085 | seq = READ_ONCE(p->mm->numa_scan_seq); |
cbee9f88 PZ |
2086 | if (p->numa_scan_seq == seq) |
2087 | return; | |
2088 | p->numa_scan_seq = seq; | |
598f0ec0 | 2089 | p->numa_scan_period_max = task_scan_max(p); |
cbee9f88 | 2090 | |
7e2703e6 RR |
2091 | total_faults = p->numa_faults_locality[0] + |
2092 | p->numa_faults_locality[1]; | |
2093 | runtime = numa_get_avg_runtime(p, &period); | |
2094 | ||
7dbd13ed MG |
2095 | /* If the task is part of a group prevent parallel updates to group stats */ |
2096 | if (p->numa_group) { | |
2097 | group_lock = &p->numa_group->lock; | |
60e69eed | 2098 | spin_lock_irq(group_lock); |
7dbd13ed MG |
2099 | } |
2100 | ||
688b7585 MG |
2101 | /* Find the node with the highest number of faults */ |
2102 | for_each_online_node(nid) { | |
44dba3d5 IM |
2103 | /* Keep track of the offsets in numa_faults array */ |
2104 | int mem_idx, membuf_idx, cpu_idx, cpubuf_idx; | |
83e1d2cd | 2105 | unsigned long faults = 0, group_faults = 0; |
44dba3d5 | 2106 | int priv; |
745d6147 | 2107 | |
be1e4e76 | 2108 | for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) { |
7e2703e6 | 2109 | long diff, f_diff, f_weight; |
8c8a743c | 2110 | |
44dba3d5 IM |
2111 | mem_idx = task_faults_idx(NUMA_MEM, nid, priv); |
2112 | membuf_idx = task_faults_idx(NUMA_MEMBUF, nid, priv); | |
2113 | cpu_idx = task_faults_idx(NUMA_CPU, nid, priv); | |
2114 | cpubuf_idx = task_faults_idx(NUMA_CPUBUF, nid, priv); | |
745d6147 | 2115 | |
ac8e895b | 2116 | /* Decay existing window, copy faults since last scan */ |
44dba3d5 IM |
2117 | diff = p->numa_faults[membuf_idx] - p->numa_faults[mem_idx] / 2; |
2118 | fault_types[priv] += p->numa_faults[membuf_idx]; | |
2119 | p->numa_faults[membuf_idx] = 0; | |
fb13c7ee | 2120 | |
7e2703e6 RR |
2121 | /* |
2122 | * Normalize the faults_from, so all tasks in a group | |
2123 | * count according to CPU use, instead of by the raw | |
2124 | * number of faults. Tasks with little runtime have | |
2125 | * little over-all impact on throughput, and thus their | |
2126 | * faults are less important. | |
2127 | */ | |
2128 | f_weight = div64_u64(runtime << 16, period + 1); | |
44dba3d5 | 2129 | f_weight = (f_weight * p->numa_faults[cpubuf_idx]) / |
7e2703e6 | 2130 | (total_faults + 1); |
44dba3d5 IM |
2131 | f_diff = f_weight - p->numa_faults[cpu_idx] / 2; |
2132 | p->numa_faults[cpubuf_idx] = 0; | |
50ec8a40 | 2133 | |
44dba3d5 IM |
2134 | p->numa_faults[mem_idx] += diff; |
2135 | p->numa_faults[cpu_idx] += f_diff; | |
2136 | faults += p->numa_faults[mem_idx]; | |
83e1d2cd | 2137 | p->total_numa_faults += diff; |
8c8a743c | 2138 | if (p->numa_group) { |
44dba3d5 IM |
2139 | /* |
2140 | * safe because we can only change our own group | |
2141 | * | |
2142 | * mem_idx represents the offset for a given | |
2143 | * nid and priv in a specific region because it | |
2144 | * is at the beginning of the numa_faults array. | |
2145 | */ | |
2146 | p->numa_group->faults[mem_idx] += diff; | |
2147 | p->numa_group->faults_cpu[mem_idx] += f_diff; | |
989348b5 | 2148 | p->numa_group->total_faults += diff; |
44dba3d5 | 2149 | group_faults += p->numa_group->faults[mem_idx]; |
8c8a743c | 2150 | } |
ac8e895b MG |
2151 | } |
2152 | ||
688b7585 MG |
2153 | if (faults > max_faults) { |
2154 | max_faults = faults; | |
2155 | max_nid = nid; | |
2156 | } | |
83e1d2cd MG |
2157 | |
2158 | if (group_faults > max_group_faults) { | |
2159 | max_group_faults = group_faults; | |
2160 | max_group_nid = nid; | |
2161 | } | |
2162 | } | |
2163 | ||
04bb2f94 RR |
2164 | update_task_scan_period(p, fault_types[0], fault_types[1]); |
2165 | ||
7dbd13ed | 2166 | if (p->numa_group) { |
4142c3eb | 2167 | numa_group_count_active_nodes(p->numa_group); |
60e69eed | 2168 | spin_unlock_irq(group_lock); |
54009416 | 2169 | max_nid = preferred_group_nid(p, max_group_nid); |
688b7585 MG |
2170 | } |
2171 | ||
bb97fc31 RR |
2172 | if (max_faults) { |
2173 | /* Set the new preferred node */ | |
2174 | if (max_nid != p->numa_preferred_nid) | |
2175 | sched_setnuma(p, max_nid); | |
2176 | ||
2177 | if (task_node(p) != p->numa_preferred_nid) | |
2178 | numa_migrate_preferred(p); | |
3a7053b3 | 2179 | } |
cbee9f88 PZ |
2180 | } |
2181 | ||
8c8a743c PZ |
2182 | static inline int get_numa_group(struct numa_group *grp) |
2183 | { | |
2184 | return atomic_inc_not_zero(&grp->refcount); | |
2185 | } | |
2186 | ||
2187 | static inline void put_numa_group(struct numa_group *grp) | |
2188 | { | |
2189 | if (atomic_dec_and_test(&grp->refcount)) | |
2190 | kfree_rcu(grp, rcu); | |
2191 | } | |
2192 | ||
3e6a9418 MG |
2193 | static void task_numa_group(struct task_struct *p, int cpupid, int flags, |
2194 | int *priv) | |
8c8a743c PZ |
2195 | { |
2196 | struct numa_group *grp, *my_grp; | |
2197 | struct task_struct *tsk; | |
2198 | bool join = false; | |
2199 | int cpu = cpupid_to_cpu(cpupid); | |
2200 | int i; | |
2201 | ||
2202 | if (unlikely(!p->numa_group)) { | |
2203 | unsigned int size = sizeof(struct numa_group) + | |
50ec8a40 | 2204 | 4*nr_node_ids*sizeof(unsigned long); |
8c8a743c PZ |
2205 | |
2206 | grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); | |
2207 | if (!grp) | |
2208 | return; | |
2209 | ||
2210 | atomic_set(&grp->refcount, 1); | |
4142c3eb RR |
2211 | grp->active_nodes = 1; |
2212 | grp->max_faults_cpu = 0; | |
8c8a743c | 2213 | spin_lock_init(&grp->lock); |
e29cf08b | 2214 | grp->gid = p->pid; |
50ec8a40 | 2215 | /* Second half of the array tracks nids where faults happen */ |
be1e4e76 RR |
2216 | grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES * |
2217 | nr_node_ids; | |
8c8a743c | 2218 | |
be1e4e76 | 2219 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
44dba3d5 | 2220 | grp->faults[i] = p->numa_faults[i]; |
8c8a743c | 2221 | |
989348b5 | 2222 | grp->total_faults = p->total_numa_faults; |
83e1d2cd | 2223 | |
8c8a743c PZ |
2224 | grp->nr_tasks++; |
2225 | rcu_assign_pointer(p->numa_group, grp); | |
2226 | } | |
2227 | ||
2228 | rcu_read_lock(); | |
316c1608 | 2229 | tsk = READ_ONCE(cpu_rq(cpu)->curr); |
8c8a743c PZ |
2230 | |
2231 | if (!cpupid_match_pid(tsk, cpupid)) | |
3354781a | 2232 | goto no_join; |
8c8a743c PZ |
2233 | |
2234 | grp = rcu_dereference(tsk->numa_group); | |
2235 | if (!grp) | |
3354781a | 2236 | goto no_join; |
8c8a743c PZ |
2237 | |
2238 | my_grp = p->numa_group; | |
2239 | if (grp == my_grp) | |
3354781a | 2240 | goto no_join; |
8c8a743c PZ |
2241 | |
2242 | /* | |
2243 | * Only join the other group if its bigger; if we're the bigger group, | |
2244 | * the other task will join us. | |
2245 | */ | |
2246 | if (my_grp->nr_tasks > grp->nr_tasks) | |
3354781a | 2247 | goto no_join; |
8c8a743c PZ |
2248 | |
2249 | /* | |
2250 | * Tie-break on the grp address. | |
2251 | */ | |
2252 | if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp) | |
3354781a | 2253 | goto no_join; |
8c8a743c | 2254 | |
dabe1d99 RR |
2255 | /* Always join threads in the same process. */ |
2256 | if (tsk->mm == current->mm) | |
2257 | join = true; | |
2258 | ||
2259 | /* Simple filter to avoid false positives due to PID collisions */ | |
2260 | if (flags & TNF_SHARED) | |
2261 | join = true; | |
8c8a743c | 2262 | |
3e6a9418 MG |
2263 | /* Update priv based on whether false sharing was detected */ |
2264 | *priv = !join; | |
2265 | ||
dabe1d99 | 2266 | if (join && !get_numa_group(grp)) |
3354781a | 2267 | goto no_join; |
8c8a743c | 2268 | |
8c8a743c PZ |
2269 | rcu_read_unlock(); |
2270 | ||
2271 | if (!join) | |
2272 | return; | |
2273 | ||
60e69eed MG |
2274 | BUG_ON(irqs_disabled()); |
2275 | double_lock_irq(&my_grp->lock, &grp->lock); | |
989348b5 | 2276 | |
be1e4e76 | 2277 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) { |
44dba3d5 IM |
2278 | my_grp->faults[i] -= p->numa_faults[i]; |
2279 | grp->faults[i] += p->numa_faults[i]; | |
8c8a743c | 2280 | } |
989348b5 MG |
2281 | my_grp->total_faults -= p->total_numa_faults; |
2282 | grp->total_faults += p->total_numa_faults; | |
8c8a743c | 2283 | |
8c8a743c PZ |
2284 | my_grp->nr_tasks--; |
2285 | grp->nr_tasks++; | |
2286 | ||
2287 | spin_unlock(&my_grp->lock); | |
60e69eed | 2288 | spin_unlock_irq(&grp->lock); |
8c8a743c PZ |
2289 | |
2290 | rcu_assign_pointer(p->numa_group, grp); | |
2291 | ||
2292 | put_numa_group(my_grp); | |
3354781a PZ |
2293 | return; |
2294 | ||
2295 | no_join: | |
2296 | rcu_read_unlock(); | |
2297 | return; | |
8c8a743c PZ |
2298 | } |
2299 | ||
2300 | void task_numa_free(struct task_struct *p) | |
2301 | { | |
2302 | struct numa_group *grp = p->numa_group; | |
44dba3d5 | 2303 | void *numa_faults = p->numa_faults; |
e9dd685c SR |
2304 | unsigned long flags; |
2305 | int i; | |
8c8a743c PZ |
2306 | |
2307 | if (grp) { | |
e9dd685c | 2308 | spin_lock_irqsave(&grp->lock, flags); |
be1e4e76 | 2309 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
44dba3d5 | 2310 | grp->faults[i] -= p->numa_faults[i]; |
989348b5 | 2311 | grp->total_faults -= p->total_numa_faults; |
83e1d2cd | 2312 | |
8c8a743c | 2313 | grp->nr_tasks--; |
e9dd685c | 2314 | spin_unlock_irqrestore(&grp->lock, flags); |
35b123e2 | 2315 | RCU_INIT_POINTER(p->numa_group, NULL); |
8c8a743c PZ |
2316 | put_numa_group(grp); |
2317 | } | |
2318 | ||
44dba3d5 | 2319 | p->numa_faults = NULL; |
82727018 | 2320 | kfree(numa_faults); |
8c8a743c PZ |
2321 | } |
2322 | ||
cbee9f88 PZ |
2323 | /* |
2324 | * Got a PROT_NONE fault for a page on @node. | |
2325 | */ | |
58b46da3 | 2326 | void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) |
cbee9f88 PZ |
2327 | { |
2328 | struct task_struct *p = current; | |
6688cc05 | 2329 | bool migrated = flags & TNF_MIGRATED; |
58b46da3 | 2330 | int cpu_node = task_node(current); |
792568ec | 2331 | int local = !!(flags & TNF_FAULT_LOCAL); |
4142c3eb | 2332 | struct numa_group *ng; |
ac8e895b | 2333 | int priv; |
cbee9f88 | 2334 | |
2a595721 | 2335 | if (!static_branch_likely(&sched_numa_balancing)) |
1a687c2e MG |
2336 | return; |
2337 | ||
9ff1d9ff MG |
2338 | /* for example, ksmd faulting in a user's mm */ |
2339 | if (!p->mm) | |
2340 | return; | |
2341 | ||
f809ca9a | 2342 | /* Allocate buffer to track faults on a per-node basis */ |
44dba3d5 IM |
2343 | if (unlikely(!p->numa_faults)) { |
2344 | int size = sizeof(*p->numa_faults) * | |
be1e4e76 | 2345 | NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids; |
f809ca9a | 2346 | |
44dba3d5 IM |
2347 | p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN); |
2348 | if (!p->numa_faults) | |
f809ca9a | 2349 | return; |
745d6147 | 2350 | |
83e1d2cd | 2351 | p->total_numa_faults = 0; |
04bb2f94 | 2352 | memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); |
f809ca9a | 2353 | } |
cbee9f88 | 2354 | |
8c8a743c PZ |
2355 | /* |
2356 | * First accesses are treated as private, otherwise consider accesses | |
2357 | * to be private if the accessing pid has not changed | |
2358 | */ | |
2359 | if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) { | |
2360 | priv = 1; | |
2361 | } else { | |
2362 | priv = cpupid_match_pid(p, last_cpupid); | |
6688cc05 | 2363 | if (!priv && !(flags & TNF_NO_GROUP)) |
3e6a9418 | 2364 | task_numa_group(p, last_cpupid, flags, &priv); |
8c8a743c PZ |
2365 | } |
2366 | ||
792568ec RR |
2367 | /* |
2368 | * If a workload spans multiple NUMA nodes, a shared fault that | |
2369 | * occurs wholly within the set of nodes that the workload is | |
2370 | * actively using should be counted as local. This allows the | |
2371 | * scan rate to slow down when a workload has settled down. | |
2372 | */ | |
4142c3eb RR |
2373 | ng = p->numa_group; |
2374 | if (!priv && !local && ng && ng->active_nodes > 1 && | |
2375 | numa_is_active_node(cpu_node, ng) && | |
2376 | numa_is_active_node(mem_node, ng)) | |
792568ec RR |
2377 | local = 1; |
2378 | ||
cbee9f88 | 2379 | task_numa_placement(p); |
f809ca9a | 2380 | |
2739d3ee RR |
2381 | /* |
2382 | * Retry task to preferred node migration periodically, in case it | |
2383 | * case it previously failed, or the scheduler moved us. | |
2384 | */ | |
2385 | if (time_after(jiffies, p->numa_migrate_retry)) | |
6b9a7460 MG |
2386 | numa_migrate_preferred(p); |
2387 | ||
b32e86b4 IM |
2388 | if (migrated) |
2389 | p->numa_pages_migrated += pages; | |
074c2381 MG |
2390 | if (flags & TNF_MIGRATE_FAIL) |
2391 | p->numa_faults_locality[2] += pages; | |
b32e86b4 | 2392 | |
44dba3d5 IM |
2393 | p->numa_faults[task_faults_idx(NUMA_MEMBUF, mem_node, priv)] += pages; |
2394 | p->numa_faults[task_faults_idx(NUMA_CPUBUF, cpu_node, priv)] += pages; | |
792568ec | 2395 | p->numa_faults_locality[local] += pages; |
cbee9f88 PZ |
2396 | } |
2397 | ||
6e5fb223 PZ |
2398 | static void reset_ptenuma_scan(struct task_struct *p) |
2399 | { | |
7e5a2c17 JL |
2400 | /* |
2401 | * We only did a read acquisition of the mmap sem, so | |
2402 | * p->mm->numa_scan_seq is written to without exclusive access | |
2403 | * and the update is not guaranteed to be atomic. That's not | |
2404 | * much of an issue though, since this is just used for | |
2405 | * statistical sampling. Use READ_ONCE/WRITE_ONCE, which are not | |
2406 | * expensive, to avoid any form of compiler optimizations: | |
2407 | */ | |
316c1608 | 2408 | WRITE_ONCE(p->mm->numa_scan_seq, READ_ONCE(p->mm->numa_scan_seq) + 1); |
6e5fb223 PZ |
2409 | p->mm->numa_scan_offset = 0; |
2410 | } | |
2411 | ||
cbee9f88 PZ |
2412 | /* |
2413 | * The expensive part of numa migration is done from task_work context. | |
2414 | * Triggered from task_tick_numa(). | |
2415 | */ | |
2416 | void task_numa_work(struct callback_head *work) | |
2417 | { | |
2418 | unsigned long migrate, next_scan, now = jiffies; | |
2419 | struct task_struct *p = current; | |
2420 | struct mm_struct *mm = p->mm; | |
51170840 | 2421 | u64 runtime = p->se.sum_exec_runtime; |
6e5fb223 | 2422 | struct vm_area_struct *vma; |
9f40604c | 2423 | unsigned long start, end; |
598f0ec0 | 2424 | unsigned long nr_pte_updates = 0; |
4620f8c1 | 2425 | long pages, virtpages; |
cbee9f88 | 2426 | |
9148a3a1 | 2427 | SCHED_WARN_ON(p != container_of(work, struct task_struct, numa_work)); |
cbee9f88 PZ |
2428 | |
2429 | work->next = work; /* protect against double add */ | |
2430 | /* | |
2431 | * Who cares about NUMA placement when they're dying. | |
2432 | * | |
2433 | * NOTE: make sure not to dereference p->mm before this check, | |
2434 | * exit_task_work() happens _after_ exit_mm() so we could be called | |
2435 | * without p->mm even though we still had it when we enqueued this | |
2436 | * work. | |
2437 | */ | |
2438 | if (p->flags & PF_EXITING) | |
2439 | return; | |
2440 | ||
930aa174 | 2441 | if (!mm->numa_next_scan) { |
7e8d16b6 MG |
2442 | mm->numa_next_scan = now + |
2443 | msecs_to_jiffies(sysctl_numa_balancing_scan_delay); | |
b8593bfd MG |
2444 | } |
2445 | ||
cbee9f88 PZ |
2446 | /* |
2447 | * Enforce maximal scan/migration frequency.. | |
2448 | */ | |
2449 | migrate = mm->numa_next_scan; | |
2450 | if (time_before(now, migrate)) | |
2451 | return; | |
2452 | ||
598f0ec0 MG |
2453 | if (p->numa_scan_period == 0) { |
2454 | p->numa_scan_period_max = task_scan_max(p); | |
2455 | p->numa_scan_period = task_scan_min(p); | |
2456 | } | |
cbee9f88 | 2457 | |
fb003b80 | 2458 | next_scan = now + msecs_to_jiffies(p->numa_scan_period); |
cbee9f88 PZ |
2459 | if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate) |
2460 | return; | |
2461 | ||
19a78d11 PZ |
2462 | /* |
2463 | * Delay this task enough that another task of this mm will likely win | |
2464 | * the next time around. | |
2465 | */ | |
2466 | p->node_stamp += 2 * TICK_NSEC; | |
2467 | ||
9f40604c MG |
2468 | start = mm->numa_scan_offset; |
2469 | pages = sysctl_numa_balancing_scan_size; | |
2470 | pages <<= 20 - PAGE_SHIFT; /* MB in pages */ | |
4620f8c1 | 2471 | virtpages = pages * 8; /* Scan up to this much virtual space */ |
9f40604c MG |
2472 | if (!pages) |
2473 | return; | |
cbee9f88 | 2474 | |
4620f8c1 | 2475 | |
6e5fb223 | 2476 | down_read(&mm->mmap_sem); |
9f40604c | 2477 | vma = find_vma(mm, start); |
6e5fb223 PZ |
2478 | if (!vma) { |
2479 | reset_ptenuma_scan(p); | |
9f40604c | 2480 | start = 0; |
6e5fb223 PZ |
2481 | vma = mm->mmap; |
2482 | } | |
9f40604c | 2483 | for (; vma; vma = vma->vm_next) { |
6b79c57b | 2484 | if (!vma_migratable(vma) || !vma_policy_mof(vma) || |
8e76d4ee | 2485 | is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) { |
6e5fb223 | 2486 | continue; |
6b79c57b | 2487 | } |
6e5fb223 | 2488 | |
4591ce4f MG |
2489 | /* |
2490 | * Shared library pages mapped by multiple processes are not | |
2491 | * migrated as it is expected they are cache replicated. Avoid | |
2492 | * hinting faults in read-only file-backed mappings or the vdso | |
2493 | * as migrating the pages will be of marginal benefit. | |
2494 | */ | |
2495 | if (!vma->vm_mm || | |
2496 | (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) | |
2497 | continue; | |
2498 | ||
3c67f474 MG |
2499 | /* |
2500 | * Skip inaccessible VMAs to avoid any confusion between | |
2501 | * PROT_NONE and NUMA hinting ptes | |
2502 | */ | |
2503 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) | |
2504 | continue; | |
4591ce4f | 2505 | |
9f40604c MG |
2506 | do { |
2507 | start = max(start, vma->vm_start); | |
2508 | end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE); | |
2509 | end = min(end, vma->vm_end); | |
4620f8c1 | 2510 | nr_pte_updates = change_prot_numa(vma, start, end); |
598f0ec0 MG |
2511 | |
2512 | /* | |
4620f8c1 RR |
2513 | * Try to scan sysctl_numa_balancing_size worth of |
2514 | * hpages that have at least one present PTE that | |
2515 | * is not already pte-numa. If the VMA contains | |
2516 | * areas that are unused or already full of prot_numa | |
2517 | * PTEs, scan up to virtpages, to skip through those | |
2518 | * areas faster. | |
598f0ec0 MG |
2519 | */ |
2520 | if (nr_pte_updates) | |
2521 | pages -= (end - start) >> PAGE_SHIFT; | |
4620f8c1 | 2522 | virtpages -= (end - start) >> PAGE_SHIFT; |
6e5fb223 | 2523 | |
9f40604c | 2524 | start = end; |
4620f8c1 | 2525 | if (pages <= 0 || virtpages <= 0) |
9f40604c | 2526 | goto out; |
3cf1962c RR |
2527 | |
2528 | cond_resched(); | |
9f40604c | 2529 | } while (end != vma->vm_end); |
cbee9f88 | 2530 | } |
6e5fb223 | 2531 | |
9f40604c | 2532 | out: |
6e5fb223 | 2533 | /* |
c69307d5 PZ |
2534 | * It is possible to reach the end of the VMA list but the last few |
2535 | * VMAs are not guaranteed to the vma_migratable. If they are not, we | |
2536 | * would find the !migratable VMA on the next scan but not reset the | |
2537 | * scanner to the start so check it now. | |
6e5fb223 PZ |
2538 | */ |
2539 | if (vma) | |
9f40604c | 2540 | mm->numa_scan_offset = start; |
6e5fb223 PZ |
2541 | else |
2542 | reset_ptenuma_scan(p); | |
2543 | up_read(&mm->mmap_sem); | |
51170840 RR |
2544 | |
2545 | /* | |
2546 | * Make sure tasks use at least 32x as much time to run other code | |
2547 | * than they used here, to limit NUMA PTE scanning overhead to 3% max. | |
2548 | * Usually update_task_scan_period slows down scanning enough; on an | |
2549 | * overloaded system we need to limit overhead on a per task basis. | |
2550 | */ | |
2551 | if (unlikely(p->se.sum_exec_runtime != runtime)) { | |
2552 | u64 diff = p->se.sum_exec_runtime - runtime; | |
2553 | p->node_stamp += 32 * diff; | |
2554 | } | |
cbee9f88 PZ |
2555 | } |
2556 | ||
2557 | /* | |
2558 | * Drive the periodic memory faults.. | |
2559 | */ | |
2560 | void task_tick_numa(struct rq *rq, struct task_struct *curr) | |
2561 | { | |
2562 | struct callback_head *work = &curr->numa_work; | |
2563 | u64 period, now; | |
2564 | ||
2565 | /* | |
2566 | * We don't care about NUMA placement if we don't have memory. | |
2567 | */ | |
2568 | if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work) | |
2569 | return; | |
2570 | ||
2571 | /* | |
2572 | * Using runtime rather than walltime has the dual advantage that | |
2573 | * we (mostly) drive the selection from busy threads and that the | |
2574 | * task needs to have done some actual work before we bother with | |
2575 | * NUMA placement. | |
2576 | */ | |
2577 | now = curr->se.sum_exec_runtime; | |
2578 | period = (u64)curr->numa_scan_period * NSEC_PER_MSEC; | |
2579 | ||
25b3e5a3 | 2580 | if (now > curr->node_stamp + period) { |
4b96a29b | 2581 | if (!curr->node_stamp) |
598f0ec0 | 2582 | curr->numa_scan_period = task_scan_min(curr); |
19a78d11 | 2583 | curr->node_stamp += period; |
cbee9f88 PZ |
2584 | |
2585 | if (!time_before(jiffies, curr->mm->numa_next_scan)) { | |
2586 | init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */ | |
2587 | task_work_add(curr, work, true); | |
2588 | } | |
2589 | } | |
2590 | } | |
2591 | #else | |
2592 | static void task_tick_numa(struct rq *rq, struct task_struct *curr) | |
2593 | { | |
2594 | } | |
0ec8aa00 PZ |
2595 | |
2596 | static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p) | |
2597 | { | |
2598 | } | |
2599 | ||
2600 | static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p) | |
2601 | { | |
2602 | } | |
cbee9f88 PZ |
2603 | #endif /* CONFIG_NUMA_BALANCING */ |
2604 | ||
30cfdcfc DA |
2605 | static void |
2606 | account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2607 | { | |
2608 | update_load_add(&cfs_rq->load, se->load.weight); | |
c09595f6 | 2609 | if (!parent_entity(se)) |
029632fb | 2610 | update_load_add(&rq_of(cfs_rq)->load, se->load.weight); |
367456c7 | 2611 | #ifdef CONFIG_SMP |
0ec8aa00 PZ |
2612 | if (entity_is_task(se)) { |
2613 | struct rq *rq = rq_of(cfs_rq); | |
2614 | ||
2615 | account_numa_enqueue(rq, task_of(se)); | |
2616 | list_add(&se->group_node, &rq->cfs_tasks); | |
2617 | } | |
367456c7 | 2618 | #endif |
30cfdcfc | 2619 | cfs_rq->nr_running++; |
30cfdcfc DA |
2620 | } |
2621 | ||
2622 | static void | |
2623 | account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2624 | { | |
2625 | update_load_sub(&cfs_rq->load, se->load.weight); | |
c09595f6 | 2626 | if (!parent_entity(se)) |
029632fb | 2627 | update_load_sub(&rq_of(cfs_rq)->load, se->load.weight); |
bfdb198c | 2628 | #ifdef CONFIG_SMP |
0ec8aa00 PZ |
2629 | if (entity_is_task(se)) { |
2630 | account_numa_dequeue(rq_of(cfs_rq), task_of(se)); | |
b87f1724 | 2631 | list_del_init(&se->group_node); |
0ec8aa00 | 2632 | } |
bfdb198c | 2633 | #endif |
30cfdcfc | 2634 | cfs_rq->nr_running--; |
30cfdcfc DA |
2635 | } |
2636 | ||
3ff6dcac YZ |
2637 | #ifdef CONFIG_FAIR_GROUP_SCHED |
2638 | # ifdef CONFIG_SMP | |
ea1dc6fc | 2639 | static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
cf5f0acf | 2640 | { |
ea1dc6fc | 2641 | long tg_weight, load, shares; |
cf5f0acf PZ |
2642 | |
2643 | /* | |
ea1dc6fc PZ |
2644 | * This really should be: cfs_rq->avg.load_avg, but instead we use |
2645 | * cfs_rq->load.weight, which is its upper bound. This helps ramp up | |
2646 | * the shares for small weight interactive tasks. | |
cf5f0acf | 2647 | */ |
ea1dc6fc | 2648 | load = scale_load_down(cfs_rq->load.weight); |
cf5f0acf | 2649 | |
ea1dc6fc | 2650 | tg_weight = atomic_long_read(&tg->load_avg); |
3ff6dcac | 2651 | |
ea1dc6fc PZ |
2652 | /* Ensure tg_weight >= load */ |
2653 | tg_weight -= cfs_rq->tg_load_avg_contrib; | |
2654 | tg_weight += load; | |
3ff6dcac | 2655 | |
3ff6dcac | 2656 | shares = (tg->shares * load); |
cf5f0acf PZ |
2657 | if (tg_weight) |
2658 | shares /= tg_weight; | |
3ff6dcac YZ |
2659 | |
2660 | if (shares < MIN_SHARES) | |
2661 | shares = MIN_SHARES; | |
2662 | if (shares > tg->shares) | |
2663 | shares = tg->shares; | |
2664 | ||
2665 | return shares; | |
2666 | } | |
3ff6dcac | 2667 | # else /* CONFIG_SMP */ |
6d5ab293 | 2668 | static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
3ff6dcac YZ |
2669 | { |
2670 | return tg->shares; | |
2671 | } | |
3ff6dcac | 2672 | # endif /* CONFIG_SMP */ |
ea1dc6fc | 2673 | |
2069dd75 PZ |
2674 | static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, |
2675 | unsigned long weight) | |
2676 | { | |
19e5eebb PT |
2677 | if (se->on_rq) { |
2678 | /* commit outstanding execution time */ | |
2679 | if (cfs_rq->curr == se) | |
2680 | update_curr(cfs_rq); | |
2069dd75 | 2681 | account_entity_dequeue(cfs_rq, se); |
19e5eebb | 2682 | } |
2069dd75 PZ |
2683 | |
2684 | update_load_set(&se->load, weight); | |
2685 | ||
2686 | if (se->on_rq) | |
2687 | account_entity_enqueue(cfs_rq, se); | |
2688 | } | |
2689 | ||
82958366 PT |
2690 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); |
2691 | ||
6d5ab293 | 2692 | static void update_cfs_shares(struct cfs_rq *cfs_rq) |
2069dd75 PZ |
2693 | { |
2694 | struct task_group *tg; | |
2695 | struct sched_entity *se; | |
3ff6dcac | 2696 | long shares; |
2069dd75 | 2697 | |
2069dd75 PZ |
2698 | tg = cfs_rq->tg; |
2699 | se = tg->se[cpu_of(rq_of(cfs_rq))]; | |
64660c86 | 2700 | if (!se || throttled_hierarchy(cfs_rq)) |
2069dd75 | 2701 | return; |
3ff6dcac YZ |
2702 | #ifndef CONFIG_SMP |
2703 | if (likely(se->load.weight == tg->shares)) | |
2704 | return; | |
2705 | #endif | |
6d5ab293 | 2706 | shares = calc_cfs_shares(cfs_rq, tg); |
2069dd75 PZ |
2707 | |
2708 | reweight_entity(cfs_rq_of(se), se, shares); | |
2709 | } | |
2710 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
6d5ab293 | 2711 | static inline void update_cfs_shares(struct cfs_rq *cfs_rq) |
2069dd75 PZ |
2712 | { |
2713 | } | |
2714 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
2715 | ||
141965c7 | 2716 | #ifdef CONFIG_SMP |
5b51f2f8 PT |
2717 | /* Precomputed fixed inverse multiplies for multiplication by y^n */ |
2718 | static const u32 runnable_avg_yN_inv[] = { | |
2719 | 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6, | |
2720 | 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85, | |
2721 | 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581, | |
2722 | 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9, | |
2723 | 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80, | |
2724 | 0x85aac367, 0x82cd8698, | |
2725 | }; | |
2726 | ||
2727 | /* | |
2728 | * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent | |
2729 | * over-estimates when re-combining. | |
2730 | */ | |
2731 | static const u32 runnable_avg_yN_sum[] = { | |
2732 | 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103, | |
2733 | 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082, | |
2734 | 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371, | |
2735 | }; | |
2736 | ||
7b20b916 YD |
2737 | /* |
2738 | * Precomputed \Sum y^k { 1<=k<=n, where n%32=0). Values are rolled down to | |
2739 | * lower integers. See Documentation/scheduler/sched-avg.txt how these | |
2740 | * were generated: | |
2741 | */ | |
2742 | static const u32 __accumulated_sum_N32[] = { | |
2743 | 0, 23371, 35056, 40899, 43820, 45281, | |
2744 | 46011, 46376, 46559, 46650, 46696, 46719, | |
2745 | }; | |
2746 | ||
9d85f21c PT |
2747 | /* |
2748 | * Approximate: | |
2749 | * val * y^n, where y^32 ~= 0.5 (~1 scheduling period) | |
2750 | */ | |
2751 | static __always_inline u64 decay_load(u64 val, u64 n) | |
2752 | { | |
5b51f2f8 PT |
2753 | unsigned int local_n; |
2754 | ||
2755 | if (!n) | |
2756 | return val; | |
2757 | else if (unlikely(n > LOAD_AVG_PERIOD * 63)) | |
2758 | return 0; | |
2759 | ||
2760 | /* after bounds checking we can collapse to 32-bit */ | |
2761 | local_n = n; | |
2762 | ||
2763 | /* | |
2764 | * As y^PERIOD = 1/2, we can combine | |
9c58c79a ZZ |
2765 | * y^n = 1/2^(n/PERIOD) * y^(n%PERIOD) |
2766 | * With a look-up table which covers y^n (n<PERIOD) | |
5b51f2f8 PT |
2767 | * |
2768 | * To achieve constant time decay_load. | |
2769 | */ | |
2770 | if (unlikely(local_n >= LOAD_AVG_PERIOD)) { | |
2771 | val >>= local_n / LOAD_AVG_PERIOD; | |
2772 | local_n %= LOAD_AVG_PERIOD; | |
9d85f21c PT |
2773 | } |
2774 | ||
9d89c257 YD |
2775 | val = mul_u64_u32_shr(val, runnable_avg_yN_inv[local_n], 32); |
2776 | return val; | |
5b51f2f8 PT |
2777 | } |
2778 | ||
2779 | /* | |
2780 | * For updates fully spanning n periods, the contribution to runnable | |
2781 | * average will be: \Sum 1024*y^n | |
2782 | * | |
2783 | * We can compute this reasonably efficiently by combining: | |
2784 | * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD} | |
2785 | */ | |
2786 | static u32 __compute_runnable_contrib(u64 n) | |
2787 | { | |
2788 | u32 contrib = 0; | |
2789 | ||
2790 | if (likely(n <= LOAD_AVG_PERIOD)) | |
2791 | return runnable_avg_yN_sum[n]; | |
2792 | else if (unlikely(n >= LOAD_AVG_MAX_N)) | |
2793 | return LOAD_AVG_MAX; | |
2794 | ||
7b20b916 YD |
2795 | /* Since n < LOAD_AVG_MAX_N, n/LOAD_AVG_PERIOD < 11 */ |
2796 | contrib = __accumulated_sum_N32[n/LOAD_AVG_PERIOD]; | |
2797 | n %= LOAD_AVG_PERIOD; | |
5b51f2f8 PT |
2798 | contrib = decay_load(contrib, n); |
2799 | return contrib + runnable_avg_yN_sum[n]; | |
9d85f21c PT |
2800 | } |
2801 | ||
54a21385 | 2802 | #define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT) |
e0f5f3af | 2803 | |
9d85f21c PT |
2804 | /* |
2805 | * We can represent the historical contribution to runnable average as the | |
2806 | * coefficients of a geometric series. To do this we sub-divide our runnable | |
2807 | * history into segments of approximately 1ms (1024us); label the segment that | |
2808 | * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g. | |
2809 | * | |
2810 | * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ... | |
2811 | * p0 p1 p2 | |
2812 | * (now) (~1ms ago) (~2ms ago) | |
2813 | * | |
2814 | * Let u_i denote the fraction of p_i that the entity was runnable. | |
2815 | * | |
2816 | * We then designate the fractions u_i as our co-efficients, yielding the | |
2817 | * following representation of historical load: | |
2818 | * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ... | |
2819 | * | |
2820 | * We choose y based on the with of a reasonably scheduling period, fixing: | |
2821 | * y^32 = 0.5 | |
2822 | * | |
2823 | * This means that the contribution to load ~32ms ago (u_32) will be weighted | |
2824 | * approximately half as much as the contribution to load within the last ms | |
2825 | * (u_0). | |
2826 | * | |
2827 | * When a period "rolls over" and we have new u_0`, multiplying the previous | |
2828 | * sum again by y is sufficient to update: | |
2829 | * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... ) | |
2830 | * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}] | |
2831 | */ | |
9d89c257 YD |
2832 | static __always_inline int |
2833 | __update_load_avg(u64 now, int cpu, struct sched_avg *sa, | |
13962234 | 2834 | unsigned long weight, int running, struct cfs_rq *cfs_rq) |
9d85f21c | 2835 | { |
e0f5f3af | 2836 | u64 delta, scaled_delta, periods; |
9d89c257 | 2837 | u32 contrib; |
6115c793 | 2838 | unsigned int delta_w, scaled_delta_w, decayed = 0; |
6f2b0452 | 2839 | unsigned long scale_freq, scale_cpu; |
9d85f21c | 2840 | |
9d89c257 | 2841 | delta = now - sa->last_update_time; |
9d85f21c PT |
2842 | /* |
2843 | * This should only happen when time goes backwards, which it | |
2844 | * unfortunately does during sched clock init when we swap over to TSC. | |
2845 | */ | |
2846 | if ((s64)delta < 0) { | |
9d89c257 | 2847 | sa->last_update_time = now; |
9d85f21c PT |
2848 | return 0; |
2849 | } | |
2850 | ||
2851 | /* | |
2852 | * Use 1024ns as the unit of measurement since it's a reasonable | |
2853 | * approximation of 1us and fast to compute. | |
2854 | */ | |
2855 | delta >>= 10; | |
2856 | if (!delta) | |
2857 | return 0; | |
9d89c257 | 2858 | sa->last_update_time = now; |
9d85f21c | 2859 | |
6f2b0452 DE |
2860 | scale_freq = arch_scale_freq_capacity(NULL, cpu); |
2861 | scale_cpu = arch_scale_cpu_capacity(NULL, cpu); | |
2862 | ||
9d85f21c | 2863 | /* delta_w is the amount already accumulated against our next period */ |
9d89c257 | 2864 | delta_w = sa->period_contrib; |
9d85f21c | 2865 | if (delta + delta_w >= 1024) { |
9d85f21c PT |
2866 | decayed = 1; |
2867 | ||
9d89c257 YD |
2868 | /* how much left for next period will start over, we don't know yet */ |
2869 | sa->period_contrib = 0; | |
2870 | ||
9d85f21c PT |
2871 | /* |
2872 | * Now that we know we're crossing a period boundary, figure | |
2873 | * out how much from delta we need to complete the current | |
2874 | * period and accrue it. | |
2875 | */ | |
2876 | delta_w = 1024 - delta_w; | |
54a21385 | 2877 | scaled_delta_w = cap_scale(delta_w, scale_freq); |
13962234 | 2878 | if (weight) { |
e0f5f3af DE |
2879 | sa->load_sum += weight * scaled_delta_w; |
2880 | if (cfs_rq) { | |
2881 | cfs_rq->runnable_load_sum += | |
2882 | weight * scaled_delta_w; | |
2883 | } | |
13962234 | 2884 | } |
36ee28e4 | 2885 | if (running) |
006cdf02 | 2886 | sa->util_sum += scaled_delta_w * scale_cpu; |
5b51f2f8 PT |
2887 | |
2888 | delta -= delta_w; | |
2889 | ||
2890 | /* Figure out how many additional periods this update spans */ | |
2891 | periods = delta / 1024; | |
2892 | delta %= 1024; | |
2893 | ||
9d89c257 | 2894 | sa->load_sum = decay_load(sa->load_sum, periods + 1); |
13962234 YD |
2895 | if (cfs_rq) { |
2896 | cfs_rq->runnable_load_sum = | |
2897 | decay_load(cfs_rq->runnable_load_sum, periods + 1); | |
2898 | } | |
9d89c257 | 2899 | sa->util_sum = decay_load((u64)(sa->util_sum), periods + 1); |
5b51f2f8 PT |
2900 | |
2901 | /* Efficiently calculate \sum (1..n_period) 1024*y^i */ | |
9d89c257 | 2902 | contrib = __compute_runnable_contrib(periods); |
54a21385 | 2903 | contrib = cap_scale(contrib, scale_freq); |
13962234 | 2904 | if (weight) { |
9d89c257 | 2905 | sa->load_sum += weight * contrib; |
13962234 YD |
2906 | if (cfs_rq) |
2907 | cfs_rq->runnable_load_sum += weight * contrib; | |
2908 | } | |
36ee28e4 | 2909 | if (running) |
006cdf02 | 2910 | sa->util_sum += contrib * scale_cpu; |
9d85f21c PT |
2911 | } |
2912 | ||
2913 | /* Remainder of delta accrued against u_0` */ | |
54a21385 | 2914 | scaled_delta = cap_scale(delta, scale_freq); |
13962234 | 2915 | if (weight) { |
e0f5f3af | 2916 | sa->load_sum += weight * scaled_delta; |
13962234 | 2917 | if (cfs_rq) |
e0f5f3af | 2918 | cfs_rq->runnable_load_sum += weight * scaled_delta; |
13962234 | 2919 | } |
36ee28e4 | 2920 | if (running) |
006cdf02 | 2921 | sa->util_sum += scaled_delta * scale_cpu; |
9ee474f5 | 2922 | |
9d89c257 | 2923 | sa->period_contrib += delta; |
9ee474f5 | 2924 | |
9d89c257 YD |
2925 | if (decayed) { |
2926 | sa->load_avg = div_u64(sa->load_sum, LOAD_AVG_MAX); | |
13962234 YD |
2927 | if (cfs_rq) { |
2928 | cfs_rq->runnable_load_avg = | |
2929 | div_u64(cfs_rq->runnable_load_sum, LOAD_AVG_MAX); | |
2930 | } | |
006cdf02 | 2931 | sa->util_avg = sa->util_sum / LOAD_AVG_MAX; |
9d89c257 | 2932 | } |
aff3e498 | 2933 | |
9d89c257 | 2934 | return decayed; |
9ee474f5 PT |
2935 | } |
2936 | ||
09a43ace VG |
2937 | /* |
2938 | * Signed add and clamp on underflow. | |
2939 | * | |
2940 | * Explicitly do a load-store to ensure the intermediate value never hits | |
2941 | * memory. This allows lockless observations without ever seeing the negative | |
2942 | * values. | |
2943 | */ | |
2944 | #define add_positive(_ptr, _val) do { \ | |
2945 | typeof(_ptr) ptr = (_ptr); \ | |
2946 | typeof(_val) val = (_val); \ | |
2947 | typeof(*ptr) res, var = READ_ONCE(*ptr); \ | |
2948 | \ | |
2949 | res = var + val; \ | |
2950 | \ | |
2951 | if (val < 0 && res > var) \ | |
2952 | res = 0; \ | |
2953 | \ | |
2954 | WRITE_ONCE(*ptr, res); \ | |
2955 | } while (0) | |
2956 | ||
c566e8e9 | 2957 | #ifdef CONFIG_FAIR_GROUP_SCHED |
7c3edd2c PZ |
2958 | /** |
2959 | * update_tg_load_avg - update the tg's load avg | |
2960 | * @cfs_rq: the cfs_rq whose avg changed | |
2961 | * @force: update regardless of how small the difference | |
2962 | * | |
2963 | * This function 'ensures': tg->load_avg := \Sum tg->cfs_rq[]->avg.load. | |
2964 | * However, because tg->load_avg is a global value there are performance | |
2965 | * considerations. | |
2966 | * | |
2967 | * In order to avoid having to look at the other cfs_rq's, we use a | |
2968 | * differential update where we store the last value we propagated. This in | |
2969 | * turn allows skipping updates if the differential is 'small'. | |
2970 | * | |
2971 | * Updating tg's load_avg is necessary before update_cfs_share() (which is | |
2972 | * done) and effective_load() (which is not done because it is too costly). | |
bb17f655 | 2973 | */ |
9d89c257 | 2974 | static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) |
bb17f655 | 2975 | { |
9d89c257 | 2976 | long delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib; |
bb17f655 | 2977 | |
aa0b7ae0 WL |
2978 | /* |
2979 | * No need to update load_avg for root_task_group as it is not used. | |
2980 | */ | |
2981 | if (cfs_rq->tg == &root_task_group) | |
2982 | return; | |
2983 | ||
9d89c257 YD |
2984 | if (force || abs(delta) > cfs_rq->tg_load_avg_contrib / 64) { |
2985 | atomic_long_add(delta, &cfs_rq->tg->load_avg); | |
2986 | cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg; | |
bb17f655 | 2987 | } |
8165e145 | 2988 | } |
f5f9739d | 2989 | |
ad936d86 BP |
2990 | /* |
2991 | * Called within set_task_rq() right before setting a task's cpu. The | |
2992 | * caller only guarantees p->pi_lock is held; no other assumptions, | |
2993 | * including the state of rq->lock, should be made. | |
2994 | */ | |
2995 | void set_task_rq_fair(struct sched_entity *se, | |
2996 | struct cfs_rq *prev, struct cfs_rq *next) | |
2997 | { | |
2998 | if (!sched_feat(ATTACH_AGE_LOAD)) | |
2999 | return; | |
3000 | ||
3001 | /* | |
3002 | * We are supposed to update the task to "current" time, then its up to | |
3003 | * date and ready to go to new CPU/cfs_rq. But we have difficulty in | |
3004 | * getting what current time is, so simply throw away the out-of-date | |
3005 | * time. This will result in the wakee task is less decayed, but giving | |
3006 | * the wakee more load sounds not bad. | |
3007 | */ | |
3008 | if (se->avg.last_update_time && prev) { | |
3009 | u64 p_last_update_time; | |
3010 | u64 n_last_update_time; | |
3011 | ||
3012 | #ifndef CONFIG_64BIT | |
3013 | u64 p_last_update_time_copy; | |
3014 | u64 n_last_update_time_copy; | |
3015 | ||
3016 | do { | |
3017 | p_last_update_time_copy = prev->load_last_update_time_copy; | |
3018 | n_last_update_time_copy = next->load_last_update_time_copy; | |
3019 | ||
3020 | smp_rmb(); | |
3021 | ||
3022 | p_last_update_time = prev->avg.last_update_time; | |
3023 | n_last_update_time = next->avg.last_update_time; | |
3024 | ||
3025 | } while (p_last_update_time != p_last_update_time_copy || | |
3026 | n_last_update_time != n_last_update_time_copy); | |
3027 | #else | |
3028 | p_last_update_time = prev->avg.last_update_time; | |
3029 | n_last_update_time = next->avg.last_update_time; | |
3030 | #endif | |
3031 | __update_load_avg(p_last_update_time, cpu_of(rq_of(prev)), | |
3032 | &se->avg, 0, 0, NULL); | |
3033 | se->avg.last_update_time = n_last_update_time; | |
3034 | } | |
3035 | } | |
09a43ace VG |
3036 | |
3037 | /* Take into account change of utilization of a child task group */ | |
3038 | static inline void | |
3039 | update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
3040 | { | |
3041 | struct cfs_rq *gcfs_rq = group_cfs_rq(se); | |
3042 | long delta = gcfs_rq->avg.util_avg - se->avg.util_avg; | |
3043 | ||
3044 | /* Nothing to update */ | |
3045 | if (!delta) | |
3046 | return; | |
3047 | ||
3048 | /* Set new sched_entity's utilization */ | |
3049 | se->avg.util_avg = gcfs_rq->avg.util_avg; | |
3050 | se->avg.util_sum = se->avg.util_avg * LOAD_AVG_MAX; | |
3051 | ||
3052 | /* Update parent cfs_rq utilization */ | |
3053 | add_positive(&cfs_rq->avg.util_avg, delta); | |
3054 | cfs_rq->avg.util_sum = cfs_rq->avg.util_avg * LOAD_AVG_MAX; | |
3055 | } | |
3056 | ||
3057 | /* Take into account change of load of a child task group */ | |
3058 | static inline void | |
3059 | update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
3060 | { | |
3061 | struct cfs_rq *gcfs_rq = group_cfs_rq(se); | |
3062 | long delta, load = gcfs_rq->avg.load_avg; | |
3063 | ||
3064 | /* | |
3065 | * If the load of group cfs_rq is null, the load of the | |
3066 | * sched_entity will also be null so we can skip the formula | |
3067 | */ | |
3068 | if (load) { | |
3069 | long tg_load; | |
3070 | ||
3071 | /* Get tg's load and ensure tg_load > 0 */ | |
3072 | tg_load = atomic_long_read(&gcfs_rq->tg->load_avg) + 1; | |
3073 | ||
3074 | /* Ensure tg_load >= load and updated with current load*/ | |
3075 | tg_load -= gcfs_rq->tg_load_avg_contrib; | |
3076 | tg_load += load; | |
3077 | ||
3078 | /* | |
3079 | * We need to compute a correction term in the case that the | |
3080 | * task group is consuming more CPU than a task of equal | |
3081 | * weight. A task with a weight equals to tg->shares will have | |
3082 | * a load less or equal to scale_load_down(tg->shares). | |
3083 | * Similarly, the sched_entities that represent the task group | |
3084 | * at parent level, can't have a load higher than | |
3085 | * scale_load_down(tg->shares). And the Sum of sched_entities' | |
3086 | * load must be <= scale_load_down(tg->shares). | |
3087 | */ | |
3088 | if (tg_load > scale_load_down(gcfs_rq->tg->shares)) { | |
3089 | /* scale gcfs_rq's load into tg's shares*/ | |
3090 | load *= scale_load_down(gcfs_rq->tg->shares); | |
3091 | load /= tg_load; | |
3092 | } | |
3093 | } | |
3094 | ||
3095 | delta = load - se->avg.load_avg; | |
3096 | ||
3097 | /* Nothing to update */ | |
3098 | if (!delta) | |
3099 | return; | |
3100 | ||
3101 | /* Set new sched_entity's load */ | |
3102 | se->avg.load_avg = load; | |
3103 | se->avg.load_sum = se->avg.load_avg * LOAD_AVG_MAX; | |
3104 | ||
3105 | /* Update parent cfs_rq load */ | |
3106 | add_positive(&cfs_rq->avg.load_avg, delta); | |
3107 | cfs_rq->avg.load_sum = cfs_rq->avg.load_avg * LOAD_AVG_MAX; | |
3108 | ||
3109 | /* | |
3110 | * If the sched_entity is already enqueued, we also have to update the | |
3111 | * runnable load avg. | |
3112 | */ | |
3113 | if (se->on_rq) { | |
3114 | /* Update parent cfs_rq runnable_load_avg */ | |
3115 | add_positive(&cfs_rq->runnable_load_avg, delta); | |
3116 | cfs_rq->runnable_load_sum = cfs_rq->runnable_load_avg * LOAD_AVG_MAX; | |
3117 | } | |
3118 | } | |
3119 | ||
3120 | static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq) | |
3121 | { | |
3122 | cfs_rq->propagate_avg = 1; | |
3123 | } | |
3124 | ||
3125 | static inline int test_and_clear_tg_cfs_propagate(struct sched_entity *se) | |
3126 | { | |
3127 | struct cfs_rq *cfs_rq = group_cfs_rq(se); | |
3128 | ||
3129 | if (!cfs_rq->propagate_avg) | |
3130 | return 0; | |
3131 | ||
3132 | cfs_rq->propagate_avg = 0; | |
3133 | return 1; | |
3134 | } | |
3135 | ||
3136 | /* Update task and its cfs_rq load average */ | |
3137 | static inline int propagate_entity_load_avg(struct sched_entity *se) | |
3138 | { | |
3139 | struct cfs_rq *cfs_rq; | |
3140 | ||
3141 | if (entity_is_task(se)) | |
3142 | return 0; | |
3143 | ||
3144 | if (!test_and_clear_tg_cfs_propagate(se)) | |
3145 | return 0; | |
3146 | ||
3147 | cfs_rq = cfs_rq_of(se); | |
3148 | ||
3149 | set_tg_cfs_propagate(cfs_rq); | |
3150 | ||
3151 | update_tg_cfs_util(cfs_rq, se); | |
3152 | update_tg_cfs_load(cfs_rq, se); | |
3153 | ||
3154 | return 1; | |
3155 | } | |
3156 | ||
6e83125c | 3157 | #else /* CONFIG_FAIR_GROUP_SCHED */ |
09a43ace | 3158 | |
9d89c257 | 3159 | static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) {} |
09a43ace VG |
3160 | |
3161 | static inline int propagate_entity_load_avg(struct sched_entity *se) | |
3162 | { | |
3163 | return 0; | |
3164 | } | |
3165 | ||
3166 | static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq) {} | |
3167 | ||
6e83125c | 3168 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
c566e8e9 | 3169 | |
a2c6c91f SM |
3170 | static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq) |
3171 | { | |
58919e83 | 3172 | if (&this_rq()->cfs == cfs_rq) { |
a2c6c91f SM |
3173 | /* |
3174 | * There are a few boundary cases this might miss but it should | |
3175 | * get called often enough that that should (hopefully) not be | |
3176 | * a real problem -- added to that it only calls on the local | |
3177 | * CPU, so if we enqueue remotely we'll miss an update, but | |
3178 | * the next tick/schedule should update. | |
3179 | * | |
3180 | * It will not get called when we go idle, because the idle | |
3181 | * thread is a different class (!fair), nor will the utilization | |
3182 | * number include things like RT tasks. | |
3183 | * | |
3184 | * As is, the util number is not freq-invariant (we'd have to | |
3185 | * implement arch_scale_freq_capacity() for that). | |
3186 | * | |
3187 | * See cpu_util(). | |
3188 | */ | |
12bde33d | 3189 | cpufreq_update_util(rq_of(cfs_rq), 0); |
a2c6c91f SM |
3190 | } |
3191 | } | |
3192 | ||
89741892 PZ |
3193 | /* |
3194 | * Unsigned subtract and clamp on underflow. | |
3195 | * | |
3196 | * Explicitly do a load-store to ensure the intermediate value never hits | |
3197 | * memory. This allows lockless observations without ever seeing the negative | |
3198 | * values. | |
3199 | */ | |
3200 | #define sub_positive(_ptr, _val) do { \ | |
3201 | typeof(_ptr) ptr = (_ptr); \ | |
3202 | typeof(*ptr) val = (_val); \ | |
3203 | typeof(*ptr) res, var = READ_ONCE(*ptr); \ | |
3204 | res = var - val; \ | |
3205 | if (res > var) \ | |
3206 | res = 0; \ | |
3207 | WRITE_ONCE(*ptr, res); \ | |
3208 | } while (0) | |
3209 | ||
3d30544f PZ |
3210 | /** |
3211 | * update_cfs_rq_load_avg - update the cfs_rq's load/util averages | |
3212 | * @now: current time, as per cfs_rq_clock_task() | |
3213 | * @cfs_rq: cfs_rq to update | |
3214 | * @update_freq: should we call cfs_rq_util_change() or will the call do so | |
3215 | * | |
3216 | * The cfs_rq avg is the direct sum of all its entities (blocked and runnable) | |
3217 | * avg. The immediate corollary is that all (fair) tasks must be attached, see | |
3218 | * post_init_entity_util_avg(). | |
3219 | * | |
3220 | * cfs_rq->avg is used for task_h_load() and update_cfs_share() for example. | |
3221 | * | |
7c3edd2c PZ |
3222 | * Returns true if the load decayed or we removed load. |
3223 | * | |
3224 | * Since both these conditions indicate a changed cfs_rq->avg.load we should | |
3225 | * call update_tg_load_avg() when this function returns true. | |
3d30544f | 3226 | */ |
a2c6c91f SM |
3227 | static inline int |
3228 | update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq) | |
2dac754e | 3229 | { |
9d89c257 | 3230 | struct sched_avg *sa = &cfs_rq->avg; |
41e0d37f | 3231 | int decayed, removed_load = 0, removed_util = 0; |
2dac754e | 3232 | |
9d89c257 | 3233 | if (atomic_long_read(&cfs_rq->removed_load_avg)) { |
9e0e83a1 | 3234 | s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0); |
89741892 PZ |
3235 | sub_positive(&sa->load_avg, r); |
3236 | sub_positive(&sa->load_sum, r * LOAD_AVG_MAX); | |
41e0d37f | 3237 | removed_load = 1; |
4e516076 | 3238 | set_tg_cfs_propagate(cfs_rq); |
8165e145 | 3239 | } |
2dac754e | 3240 | |
9d89c257 YD |
3241 | if (atomic_long_read(&cfs_rq->removed_util_avg)) { |
3242 | long r = atomic_long_xchg(&cfs_rq->removed_util_avg, 0); | |
89741892 PZ |
3243 | sub_positive(&sa->util_avg, r); |
3244 | sub_positive(&sa->util_sum, r * LOAD_AVG_MAX); | |
41e0d37f | 3245 | removed_util = 1; |
4e516076 | 3246 | set_tg_cfs_propagate(cfs_rq); |
9d89c257 | 3247 | } |
36ee28e4 | 3248 | |
a2c6c91f | 3249 | decayed = __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa, |
13962234 | 3250 | scale_load_down(cfs_rq->load.weight), cfs_rq->curr != NULL, cfs_rq); |
36ee28e4 | 3251 | |
9d89c257 YD |
3252 | #ifndef CONFIG_64BIT |
3253 | smp_wmb(); | |
3254 | cfs_rq->load_last_update_time_copy = sa->last_update_time; | |
3255 | #endif | |
36ee28e4 | 3256 | |
a2c6c91f SM |
3257 | if (update_freq && (decayed || removed_util)) |
3258 | cfs_rq_util_change(cfs_rq); | |
21e96f88 | 3259 | |
41e0d37f | 3260 | return decayed || removed_load; |
21e96f88 SM |
3261 | } |
3262 | ||
d31b1a66 VG |
3263 | /* |
3264 | * Optional action to be done while updating the load average | |
3265 | */ | |
3266 | #define UPDATE_TG 0x1 | |
3267 | #define SKIP_AGE_LOAD 0x2 | |
3268 | ||
21e96f88 | 3269 | /* Update task and its cfs_rq load average */ |
d31b1a66 | 3270 | static inline void update_load_avg(struct sched_entity *se, int flags) |
21e96f88 SM |
3271 | { |
3272 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
3273 | u64 now = cfs_rq_clock_task(cfs_rq); | |
3274 | struct rq *rq = rq_of(cfs_rq); | |
3275 | int cpu = cpu_of(rq); | |
09a43ace | 3276 | int decayed; |
21e96f88 SM |
3277 | |
3278 | /* | |
3279 | * Track task load average for carrying it to new CPU after migrated, and | |
3280 | * track group sched_entity load average for task_h_load calc in migration | |
3281 | */ | |
d31b1a66 VG |
3282 | if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD)) { |
3283 | __update_load_avg(now, cpu, &se->avg, | |
21e96f88 SM |
3284 | se->on_rq * scale_load_down(se->load.weight), |
3285 | cfs_rq->curr == se, NULL); | |
d31b1a66 | 3286 | } |
21e96f88 | 3287 | |
09a43ace VG |
3288 | decayed = update_cfs_rq_load_avg(now, cfs_rq, true); |
3289 | decayed |= propagate_entity_load_avg(se); | |
3290 | ||
3291 | if (decayed && (flags & UPDATE_TG)) | |
21e96f88 | 3292 | update_tg_load_avg(cfs_rq, 0); |
9ee474f5 PT |
3293 | } |
3294 | ||
3d30544f PZ |
3295 | /** |
3296 | * attach_entity_load_avg - attach this entity to its cfs_rq load avg | |
3297 | * @cfs_rq: cfs_rq to attach to | |
3298 | * @se: sched_entity to attach | |
3299 | * | |
3300 | * Must call update_cfs_rq_load_avg() before this, since we rely on | |
3301 | * cfs_rq->avg.last_update_time being current. | |
3302 | */ | |
a05e8c51 BP |
3303 | static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) |
3304 | { | |
3305 | se->avg.last_update_time = cfs_rq->avg.last_update_time; | |
3306 | cfs_rq->avg.load_avg += se->avg.load_avg; | |
3307 | cfs_rq->avg.load_sum += se->avg.load_sum; | |
3308 | cfs_rq->avg.util_avg += se->avg.util_avg; | |
3309 | cfs_rq->avg.util_sum += se->avg.util_sum; | |
09a43ace | 3310 | set_tg_cfs_propagate(cfs_rq); |
a2c6c91f SM |
3311 | |
3312 | cfs_rq_util_change(cfs_rq); | |
a05e8c51 BP |
3313 | } |
3314 | ||
3d30544f PZ |
3315 | /** |
3316 | * detach_entity_load_avg - detach this entity from its cfs_rq load avg | |
3317 | * @cfs_rq: cfs_rq to detach from | |
3318 | * @se: sched_entity to detach | |
3319 | * | |
3320 | * Must call update_cfs_rq_load_avg() before this, since we rely on | |
3321 | * cfs_rq->avg.last_update_time being current. | |
3322 | */ | |
a05e8c51 BP |
3323 | static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) |
3324 | { | |
a05e8c51 | 3325 | |
89741892 PZ |
3326 | sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg); |
3327 | sub_positive(&cfs_rq->avg.load_sum, se->avg.load_sum); | |
3328 | sub_positive(&cfs_rq->avg.util_avg, se->avg.util_avg); | |
3329 | sub_positive(&cfs_rq->avg.util_sum, se->avg.util_sum); | |
09a43ace | 3330 | set_tg_cfs_propagate(cfs_rq); |
a2c6c91f SM |
3331 | |
3332 | cfs_rq_util_change(cfs_rq); | |
a05e8c51 BP |
3333 | } |
3334 | ||
9d89c257 YD |
3335 | /* Add the load generated by se into cfs_rq's load average */ |
3336 | static inline void | |
3337 | enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
9ee474f5 | 3338 | { |
9d89c257 | 3339 | struct sched_avg *sa = &se->avg; |
18bf2805 | 3340 | |
13962234 YD |
3341 | cfs_rq->runnable_load_avg += sa->load_avg; |
3342 | cfs_rq->runnable_load_sum += sa->load_sum; | |
3343 | ||
d31b1a66 | 3344 | if (!sa->last_update_time) { |
a05e8c51 | 3345 | attach_entity_load_avg(cfs_rq, se); |
9d89c257 | 3346 | update_tg_load_avg(cfs_rq, 0); |
d31b1a66 | 3347 | } |
2dac754e PT |
3348 | } |
3349 | ||
13962234 YD |
3350 | /* Remove the runnable load generated by se from cfs_rq's runnable load average */ |
3351 | static inline void | |
3352 | dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
3353 | { | |
13962234 YD |
3354 | cfs_rq->runnable_load_avg = |
3355 | max_t(long, cfs_rq->runnable_load_avg - se->avg.load_avg, 0); | |
3356 | cfs_rq->runnable_load_sum = | |
a05e8c51 | 3357 | max_t(s64, cfs_rq->runnable_load_sum - se->avg.load_sum, 0); |
13962234 YD |
3358 | } |
3359 | ||
9d89c257 | 3360 | #ifndef CONFIG_64BIT |
0905f04e YD |
3361 | static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq) |
3362 | { | |
9d89c257 | 3363 | u64 last_update_time_copy; |
0905f04e | 3364 | u64 last_update_time; |
9ee474f5 | 3365 | |
9d89c257 YD |
3366 | do { |
3367 | last_update_time_copy = cfs_rq->load_last_update_time_copy; | |
3368 | smp_rmb(); | |
3369 | last_update_time = cfs_rq->avg.last_update_time; | |
3370 | } while (last_update_time != last_update_time_copy); | |
0905f04e YD |
3371 | |
3372 | return last_update_time; | |
3373 | } | |
9d89c257 | 3374 | #else |
0905f04e YD |
3375 | static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq) |
3376 | { | |
3377 | return cfs_rq->avg.last_update_time; | |
3378 | } | |
9d89c257 YD |
3379 | #endif |
3380 | ||
104cb16d MR |
3381 | /* |
3382 | * Synchronize entity load avg of dequeued entity without locking | |
3383 | * the previous rq. | |
3384 | */ | |
3385 | void sync_entity_load_avg(struct sched_entity *se) | |
3386 | { | |
3387 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
3388 | u64 last_update_time; | |
3389 | ||
3390 | last_update_time = cfs_rq_last_update_time(cfs_rq); | |
3391 | __update_load_avg(last_update_time, cpu_of(rq_of(cfs_rq)), &se->avg, 0, 0, NULL); | |
3392 | } | |
3393 | ||
0905f04e YD |
3394 | /* |
3395 | * Task first catches up with cfs_rq, and then subtract | |
3396 | * itself from the cfs_rq (task must be off the queue now). | |
3397 | */ | |
3398 | void remove_entity_load_avg(struct sched_entity *se) | |
3399 | { | |
3400 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
0905f04e YD |
3401 | |
3402 | /* | |
7dc603c9 PZ |
3403 | * tasks cannot exit without having gone through wake_up_new_task() -> |
3404 | * post_init_entity_util_avg() which will have added things to the | |
3405 | * cfs_rq, so we can remove unconditionally. | |
3406 | * | |
3407 | * Similarly for groups, they will have passed through | |
3408 | * post_init_entity_util_avg() before unregister_sched_fair_group() | |
3409 | * calls this. | |
0905f04e | 3410 | */ |
0905f04e | 3411 | |
104cb16d | 3412 | sync_entity_load_avg(se); |
9d89c257 YD |
3413 | atomic_long_add(se->avg.load_avg, &cfs_rq->removed_load_avg); |
3414 | atomic_long_add(se->avg.util_avg, &cfs_rq->removed_util_avg); | |
2dac754e | 3415 | } |
642dbc39 | 3416 | |
7ea241af YD |
3417 | static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq *cfs_rq) |
3418 | { | |
3419 | return cfs_rq->runnable_load_avg; | |
3420 | } | |
3421 | ||
3422 | static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq) | |
3423 | { | |
3424 | return cfs_rq->avg.load_avg; | |
3425 | } | |
3426 | ||
46f69fa3 | 3427 | static int idle_balance(struct rq *this_rq, struct rq_flags *rf); |
6e83125c | 3428 | |
38033c37 PZ |
3429 | #else /* CONFIG_SMP */ |
3430 | ||
01011473 PZ |
3431 | static inline int |
3432 | update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq) | |
3433 | { | |
3434 | return 0; | |
3435 | } | |
3436 | ||
d31b1a66 VG |
3437 | #define UPDATE_TG 0x0 |
3438 | #define SKIP_AGE_LOAD 0x0 | |
3439 | ||
3440 | static inline void update_load_avg(struct sched_entity *se, int not_used1) | |
536bd00c | 3441 | { |
12bde33d | 3442 | cpufreq_update_util(rq_of(cfs_rq_of(se)), 0); |
536bd00c RW |
3443 | } |
3444 | ||
9d89c257 YD |
3445 | static inline void |
3446 | enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} | |
13962234 YD |
3447 | static inline void |
3448 | dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} | |
9d89c257 | 3449 | static inline void remove_entity_load_avg(struct sched_entity *se) {} |
6e83125c | 3450 | |
a05e8c51 BP |
3451 | static inline void |
3452 | attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} | |
3453 | static inline void | |
3454 | detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} | |
3455 | ||
46f69fa3 | 3456 | static inline int idle_balance(struct rq *rq, struct rq_flags *rf) |
6e83125c PZ |
3457 | { |
3458 | return 0; | |
3459 | } | |
3460 | ||
38033c37 | 3461 | #endif /* CONFIG_SMP */ |
9d85f21c | 3462 | |
ddc97297 PZ |
3463 | static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se) |
3464 | { | |
3465 | #ifdef CONFIG_SCHED_DEBUG | |
3466 | s64 d = se->vruntime - cfs_rq->min_vruntime; | |
3467 | ||
3468 | if (d < 0) | |
3469 | d = -d; | |
3470 | ||
3471 | if (d > 3*sysctl_sched_latency) | |
ae92882e | 3472 | schedstat_inc(cfs_rq->nr_spread_over); |
ddc97297 PZ |
3473 | #endif |
3474 | } | |
3475 | ||
aeb73b04 PZ |
3476 | static void |
3477 | place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) | |
3478 | { | |
1af5f730 | 3479 | u64 vruntime = cfs_rq->min_vruntime; |
94dfb5e7 | 3480 | |
2cb8600e PZ |
3481 | /* |
3482 | * The 'current' period is already promised to the current tasks, | |
3483 | * however the extra weight of the new task will slow them down a | |
3484 | * little, place the new task so that it fits in the slot that | |
3485 | * stays open at the end. | |
3486 | */ | |
94dfb5e7 | 3487 | if (initial && sched_feat(START_DEBIT)) |
f9c0b095 | 3488 | vruntime += sched_vslice(cfs_rq, se); |
aeb73b04 | 3489 | |
a2e7a7eb | 3490 | /* sleeps up to a single latency don't count. */ |
5ca9880c | 3491 | if (!initial) { |
a2e7a7eb | 3492 | unsigned long thresh = sysctl_sched_latency; |
a7be37ac | 3493 | |
a2e7a7eb MG |
3494 | /* |
3495 | * Halve their sleep time's effect, to allow | |
3496 | * for a gentler effect of sleepers: | |
3497 | */ | |
3498 | if (sched_feat(GENTLE_FAIR_SLEEPERS)) | |
3499 | thresh >>= 1; | |
51e0304c | 3500 | |
a2e7a7eb | 3501 | vruntime -= thresh; |
aeb73b04 PZ |
3502 | } |
3503 | ||
b5d9d734 | 3504 | /* ensure we never gain time by being placed backwards. */ |
16c8f1c7 | 3505 | se->vruntime = max_vruntime(se->vruntime, vruntime); |
aeb73b04 PZ |
3506 | } |
3507 | ||
d3d9dc33 PT |
3508 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq); |
3509 | ||
cb251765 MG |
3510 | static inline void check_schedstat_required(void) |
3511 | { | |
3512 | #ifdef CONFIG_SCHEDSTATS | |
3513 | if (schedstat_enabled()) | |
3514 | return; | |
3515 | ||
3516 | /* Force schedstat enabled if a dependent tracepoint is active */ | |
3517 | if (trace_sched_stat_wait_enabled() || | |
3518 | trace_sched_stat_sleep_enabled() || | |
3519 | trace_sched_stat_iowait_enabled() || | |
3520 | trace_sched_stat_blocked_enabled() || | |
3521 | trace_sched_stat_runtime_enabled()) { | |
eda8dca5 | 3522 | printk_deferred_once("Scheduler tracepoints stat_sleep, stat_iowait, " |
cb251765 MG |
3523 | "stat_blocked and stat_runtime require the " |
3524 | "kernel parameter schedstats=enabled or " | |
3525 | "kernel.sched_schedstats=1\n"); | |
3526 | } | |
3527 | #endif | |
3528 | } | |
3529 | ||
b5179ac7 PZ |
3530 | |
3531 | /* | |
3532 | * MIGRATION | |
3533 | * | |
3534 | * dequeue | |
3535 | * update_curr() | |
3536 | * update_min_vruntime() | |
3537 | * vruntime -= min_vruntime | |
3538 | * | |
3539 | * enqueue | |
3540 | * update_curr() | |
3541 | * update_min_vruntime() | |
3542 | * vruntime += min_vruntime | |
3543 | * | |
3544 | * this way the vruntime transition between RQs is done when both | |
3545 | * min_vruntime are up-to-date. | |
3546 | * | |
3547 | * WAKEUP (remote) | |
3548 | * | |
59efa0ba | 3549 | * ->migrate_task_rq_fair() (p->state == TASK_WAKING) |
b5179ac7 PZ |
3550 | * vruntime -= min_vruntime |
3551 | * | |
3552 | * enqueue | |
3553 | * update_curr() | |
3554 | * update_min_vruntime() | |
3555 | * vruntime += min_vruntime | |
3556 | * | |
3557 | * this way we don't have the most up-to-date min_vruntime on the originating | |
3558 | * CPU and an up-to-date min_vruntime on the destination CPU. | |
3559 | */ | |
3560 | ||
bf0f6f24 | 3561 | static void |
88ec22d3 | 3562 | enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 3563 | { |
2f950354 PZ |
3564 | bool renorm = !(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATED); |
3565 | bool curr = cfs_rq->curr == se; | |
3566 | ||
88ec22d3 | 3567 | /* |
2f950354 PZ |
3568 | * If we're the current task, we must renormalise before calling |
3569 | * update_curr(). | |
88ec22d3 | 3570 | */ |
2f950354 | 3571 | if (renorm && curr) |
88ec22d3 PZ |
3572 | se->vruntime += cfs_rq->min_vruntime; |
3573 | ||
2f950354 PZ |
3574 | update_curr(cfs_rq); |
3575 | ||
bf0f6f24 | 3576 | /* |
2f950354 PZ |
3577 | * Otherwise, renormalise after, such that we're placed at the current |
3578 | * moment in time, instead of some random moment in the past. Being | |
3579 | * placed in the past could significantly boost this task to the | |
3580 | * fairness detriment of existing tasks. | |
bf0f6f24 | 3581 | */ |
2f950354 PZ |
3582 | if (renorm && !curr) |
3583 | se->vruntime += cfs_rq->min_vruntime; | |
3584 | ||
d31b1a66 | 3585 | update_load_avg(se, UPDATE_TG); |
9d89c257 | 3586 | enqueue_entity_load_avg(cfs_rq, se); |
17bc14b7 LT |
3587 | account_entity_enqueue(cfs_rq, se); |
3588 | update_cfs_shares(cfs_rq); | |
bf0f6f24 | 3589 | |
1a3d027c | 3590 | if (flags & ENQUEUE_WAKEUP) |
aeb73b04 | 3591 | place_entity(cfs_rq, se, 0); |
bf0f6f24 | 3592 | |
cb251765 | 3593 | check_schedstat_required(); |
4fa8d299 JP |
3594 | update_stats_enqueue(cfs_rq, se, flags); |
3595 | check_spread(cfs_rq, se); | |
2f950354 | 3596 | if (!curr) |
83b699ed | 3597 | __enqueue_entity(cfs_rq, se); |
2069dd75 | 3598 | se->on_rq = 1; |
3d4b47b4 | 3599 | |
d3d9dc33 | 3600 | if (cfs_rq->nr_running == 1) { |
3d4b47b4 | 3601 | list_add_leaf_cfs_rq(cfs_rq); |
d3d9dc33 PT |
3602 | check_enqueue_throttle(cfs_rq); |
3603 | } | |
bf0f6f24 IM |
3604 | } |
3605 | ||
2c13c919 | 3606 | static void __clear_buddies_last(struct sched_entity *se) |
2002c695 | 3607 | { |
2c13c919 RR |
3608 | for_each_sched_entity(se) { |
3609 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 3610 | if (cfs_rq->last != se) |
2c13c919 | 3611 | break; |
f1044799 PZ |
3612 | |
3613 | cfs_rq->last = NULL; | |
2c13c919 RR |
3614 | } |
3615 | } | |
2002c695 | 3616 | |
2c13c919 RR |
3617 | static void __clear_buddies_next(struct sched_entity *se) |
3618 | { | |
3619 | for_each_sched_entity(se) { | |
3620 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 3621 | if (cfs_rq->next != se) |
2c13c919 | 3622 | break; |
f1044799 PZ |
3623 | |
3624 | cfs_rq->next = NULL; | |
2c13c919 | 3625 | } |
2002c695 PZ |
3626 | } |
3627 | ||
ac53db59 RR |
3628 | static void __clear_buddies_skip(struct sched_entity *se) |
3629 | { | |
3630 | for_each_sched_entity(se) { | |
3631 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 3632 | if (cfs_rq->skip != se) |
ac53db59 | 3633 | break; |
f1044799 PZ |
3634 | |
3635 | cfs_rq->skip = NULL; | |
ac53db59 RR |
3636 | } |
3637 | } | |
3638 | ||
a571bbea PZ |
3639 | static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) |
3640 | { | |
2c13c919 RR |
3641 | if (cfs_rq->last == se) |
3642 | __clear_buddies_last(se); | |
3643 | ||
3644 | if (cfs_rq->next == se) | |
3645 | __clear_buddies_next(se); | |
ac53db59 RR |
3646 | |
3647 | if (cfs_rq->skip == se) | |
3648 | __clear_buddies_skip(se); | |
a571bbea PZ |
3649 | } |
3650 | ||
6c16a6dc | 3651 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
d8b4986d | 3652 | |
bf0f6f24 | 3653 | static void |
371fd7e7 | 3654 | dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 3655 | { |
a2a2d680 DA |
3656 | /* |
3657 | * Update run-time statistics of the 'current'. | |
3658 | */ | |
3659 | update_curr(cfs_rq); | |
d31b1a66 | 3660 | update_load_avg(se, UPDATE_TG); |
13962234 | 3661 | dequeue_entity_load_avg(cfs_rq, se); |
a2a2d680 | 3662 | |
4fa8d299 | 3663 | update_stats_dequeue(cfs_rq, se, flags); |
67e9fb2a | 3664 | |
2002c695 | 3665 | clear_buddies(cfs_rq, se); |
4793241b | 3666 | |
83b699ed | 3667 | if (se != cfs_rq->curr) |
30cfdcfc | 3668 | __dequeue_entity(cfs_rq, se); |
17bc14b7 | 3669 | se->on_rq = 0; |
30cfdcfc | 3670 | account_entity_dequeue(cfs_rq, se); |
88ec22d3 PZ |
3671 | |
3672 | /* | |
b60205c7 PZ |
3673 | * Normalize after update_curr(); which will also have moved |
3674 | * min_vruntime if @se is the one holding it back. But before doing | |
3675 | * update_min_vruntime() again, which will discount @se's position and | |
3676 | * can move min_vruntime forward still more. | |
88ec22d3 | 3677 | */ |
371fd7e7 | 3678 | if (!(flags & DEQUEUE_SLEEP)) |
88ec22d3 | 3679 | se->vruntime -= cfs_rq->min_vruntime; |
1e876231 | 3680 | |
d8b4986d PT |
3681 | /* return excess runtime on last dequeue */ |
3682 | return_cfs_rq_runtime(cfs_rq); | |
3683 | ||
17bc14b7 | 3684 | update_cfs_shares(cfs_rq); |
b60205c7 PZ |
3685 | |
3686 | /* | |
3687 | * Now advance min_vruntime if @se was the entity holding it back, | |
3688 | * except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be | |
3689 | * put back on, and if we advance min_vruntime, we'll be placed back | |
3690 | * further than we started -- ie. we'll be penalized. | |
3691 | */ | |
3692 | if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE) | |
3693 | update_min_vruntime(cfs_rq); | |
bf0f6f24 IM |
3694 | } |
3695 | ||
3696 | /* | |
3697 | * Preempt the current task with a newly woken task if needed: | |
3698 | */ | |
7c92e54f | 3699 | static void |
2e09bf55 | 3700 | check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
bf0f6f24 | 3701 | { |
11697830 | 3702 | unsigned long ideal_runtime, delta_exec; |
f4cfb33e WX |
3703 | struct sched_entity *se; |
3704 | s64 delta; | |
11697830 | 3705 | |
6d0f0ebd | 3706 | ideal_runtime = sched_slice(cfs_rq, curr); |
11697830 | 3707 | delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; |
a9f3e2b5 | 3708 | if (delta_exec > ideal_runtime) { |
8875125e | 3709 | resched_curr(rq_of(cfs_rq)); |
a9f3e2b5 MG |
3710 | /* |
3711 | * The current task ran long enough, ensure it doesn't get | |
3712 | * re-elected due to buddy favours. | |
3713 | */ | |
3714 | clear_buddies(cfs_rq, curr); | |
f685ceac MG |
3715 | return; |
3716 | } | |
3717 | ||
3718 | /* | |
3719 | * Ensure that a task that missed wakeup preemption by a | |
3720 | * narrow margin doesn't have to wait for a full slice. | |
3721 | * This also mitigates buddy induced latencies under load. | |
3722 | */ | |
f685ceac MG |
3723 | if (delta_exec < sysctl_sched_min_granularity) |
3724 | return; | |
3725 | ||
f4cfb33e WX |
3726 | se = __pick_first_entity(cfs_rq); |
3727 | delta = curr->vruntime - se->vruntime; | |
f685ceac | 3728 | |
f4cfb33e WX |
3729 | if (delta < 0) |
3730 | return; | |
d7d82944 | 3731 | |
f4cfb33e | 3732 | if (delta > ideal_runtime) |
8875125e | 3733 | resched_curr(rq_of(cfs_rq)); |
bf0f6f24 IM |
3734 | } |
3735 | ||
83b699ed | 3736 | static void |
8494f412 | 3737 | set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 3738 | { |
83b699ed SV |
3739 | /* 'current' is not kept within the tree. */ |
3740 | if (se->on_rq) { | |
3741 | /* | |
3742 | * Any task has to be enqueued before it get to execute on | |
3743 | * a CPU. So account for the time it spent waiting on the | |
3744 | * runqueue. | |
3745 | */ | |
4fa8d299 | 3746 | update_stats_wait_end(cfs_rq, se); |
83b699ed | 3747 | __dequeue_entity(cfs_rq, se); |
d31b1a66 | 3748 | update_load_avg(se, UPDATE_TG); |
83b699ed SV |
3749 | } |
3750 | ||
79303e9e | 3751 | update_stats_curr_start(cfs_rq, se); |
429d43bc | 3752 | cfs_rq->curr = se; |
4fa8d299 | 3753 | |
eba1ed4b IM |
3754 | /* |
3755 | * Track our maximum slice length, if the CPU's load is at | |
3756 | * least twice that of our own weight (i.e. dont track it | |
3757 | * when there are only lesser-weight tasks around): | |
3758 | */ | |
cb251765 | 3759 | if (schedstat_enabled() && rq_of(cfs_rq)->load.weight >= 2*se->load.weight) { |
4fa8d299 JP |
3760 | schedstat_set(se->statistics.slice_max, |
3761 | max((u64)schedstat_val(se->statistics.slice_max), | |
3762 | se->sum_exec_runtime - se->prev_sum_exec_runtime)); | |
eba1ed4b | 3763 | } |
4fa8d299 | 3764 | |
4a55b450 | 3765 | se->prev_sum_exec_runtime = se->sum_exec_runtime; |
bf0f6f24 IM |
3766 | } |
3767 | ||
3f3a4904 PZ |
3768 | static int |
3769 | wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se); | |
3770 | ||
ac53db59 RR |
3771 | /* |
3772 | * Pick the next process, keeping these things in mind, in this order: | |
3773 | * 1) keep things fair between processes/task groups | |
3774 | * 2) pick the "next" process, since someone really wants that to run | |
3775 | * 3) pick the "last" process, for cache locality | |
3776 | * 4) do not run the "skip" process, if something else is available | |
3777 | */ | |
678d5718 PZ |
3778 | static struct sched_entity * |
3779 | pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) | |
aa2ac252 | 3780 | { |
678d5718 PZ |
3781 | struct sched_entity *left = __pick_first_entity(cfs_rq); |
3782 | struct sched_entity *se; | |
3783 | ||
3784 | /* | |
3785 | * If curr is set we have to see if its left of the leftmost entity | |
3786 | * still in the tree, provided there was anything in the tree at all. | |
3787 | */ | |
3788 | if (!left || (curr && entity_before(curr, left))) | |
3789 | left = curr; | |
3790 | ||
3791 | se = left; /* ideally we run the leftmost entity */ | |
f4b6755f | 3792 | |
ac53db59 RR |
3793 | /* |
3794 | * Avoid running the skip buddy, if running something else can | |
3795 | * be done without getting too unfair. | |
3796 | */ | |
3797 | if (cfs_rq->skip == se) { | |
678d5718 PZ |
3798 | struct sched_entity *second; |
3799 | ||
3800 | if (se == curr) { | |
3801 | second = __pick_first_entity(cfs_rq); | |
3802 | } else { | |
3803 | second = __pick_next_entity(se); | |
3804 | if (!second || (curr && entity_before(curr, second))) | |
3805 | second = curr; | |
3806 | } | |
3807 | ||
ac53db59 RR |
3808 | if (second && wakeup_preempt_entity(second, left) < 1) |
3809 | se = second; | |
3810 | } | |
aa2ac252 | 3811 | |
f685ceac MG |
3812 | /* |
3813 | * Prefer last buddy, try to return the CPU to a preempted task. | |
3814 | */ | |
3815 | if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) | |
3816 | se = cfs_rq->last; | |
3817 | ||
ac53db59 RR |
3818 | /* |
3819 | * Someone really wants this to run. If it's not unfair, run it. | |
3820 | */ | |
3821 | if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) | |
3822 | se = cfs_rq->next; | |
3823 | ||
f685ceac | 3824 | clear_buddies(cfs_rq, se); |
4793241b PZ |
3825 | |
3826 | return se; | |
aa2ac252 PZ |
3827 | } |
3828 | ||
678d5718 | 3829 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
d3d9dc33 | 3830 | |
ab6cde26 | 3831 | static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) |
bf0f6f24 IM |
3832 | { |
3833 | /* | |
3834 | * If still on the runqueue then deactivate_task() | |
3835 | * was not called and update_curr() has to be done: | |
3836 | */ | |
3837 | if (prev->on_rq) | |
b7cc0896 | 3838 | update_curr(cfs_rq); |
bf0f6f24 | 3839 | |
d3d9dc33 PT |
3840 | /* throttle cfs_rqs exceeding runtime */ |
3841 | check_cfs_rq_runtime(cfs_rq); | |
3842 | ||
4fa8d299 | 3843 | check_spread(cfs_rq, prev); |
cb251765 | 3844 | |
30cfdcfc | 3845 | if (prev->on_rq) { |
4fa8d299 | 3846 | update_stats_wait_start(cfs_rq, prev); |
30cfdcfc DA |
3847 | /* Put 'current' back into the tree. */ |
3848 | __enqueue_entity(cfs_rq, prev); | |
9d85f21c | 3849 | /* in !on_rq case, update occurred at dequeue */ |
9d89c257 | 3850 | update_load_avg(prev, 0); |
30cfdcfc | 3851 | } |
429d43bc | 3852 | cfs_rq->curr = NULL; |
bf0f6f24 IM |
3853 | } |
3854 | ||
8f4d37ec PZ |
3855 | static void |
3856 | entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) | |
bf0f6f24 | 3857 | { |
bf0f6f24 | 3858 | /* |
30cfdcfc | 3859 | * Update run-time statistics of the 'current'. |
bf0f6f24 | 3860 | */ |
30cfdcfc | 3861 | update_curr(cfs_rq); |
bf0f6f24 | 3862 | |
9d85f21c PT |
3863 | /* |
3864 | * Ensure that runnable average is periodically updated. | |
3865 | */ | |
d31b1a66 | 3866 | update_load_avg(curr, UPDATE_TG); |
bf0bd948 | 3867 | update_cfs_shares(cfs_rq); |
9d85f21c | 3868 | |
8f4d37ec PZ |
3869 | #ifdef CONFIG_SCHED_HRTICK |
3870 | /* | |
3871 | * queued ticks are scheduled to match the slice, so don't bother | |
3872 | * validating it and just reschedule. | |
3873 | */ | |
983ed7a6 | 3874 | if (queued) { |
8875125e | 3875 | resched_curr(rq_of(cfs_rq)); |
983ed7a6 HH |
3876 | return; |
3877 | } | |
8f4d37ec PZ |
3878 | /* |
3879 | * don't let the period tick interfere with the hrtick preemption | |
3880 | */ | |
3881 | if (!sched_feat(DOUBLE_TICK) && | |
3882 | hrtimer_active(&rq_of(cfs_rq)->hrtick_timer)) | |
3883 | return; | |
3884 | #endif | |
3885 | ||
2c2efaed | 3886 | if (cfs_rq->nr_running > 1) |
2e09bf55 | 3887 | check_preempt_tick(cfs_rq, curr); |
bf0f6f24 IM |
3888 | } |
3889 | ||
ab84d31e PT |
3890 | |
3891 | /************************************************** | |
3892 | * CFS bandwidth control machinery | |
3893 | */ | |
3894 | ||
3895 | #ifdef CONFIG_CFS_BANDWIDTH | |
029632fb PZ |
3896 | |
3897 | #ifdef HAVE_JUMP_LABEL | |
c5905afb | 3898 | static struct static_key __cfs_bandwidth_used; |
029632fb PZ |
3899 | |
3900 | static inline bool cfs_bandwidth_used(void) | |
3901 | { | |
c5905afb | 3902 | return static_key_false(&__cfs_bandwidth_used); |
029632fb PZ |
3903 | } |
3904 | ||
1ee14e6c | 3905 | void cfs_bandwidth_usage_inc(void) |
029632fb | 3906 | { |
1ee14e6c BS |
3907 | static_key_slow_inc(&__cfs_bandwidth_used); |
3908 | } | |
3909 | ||
3910 | void cfs_bandwidth_usage_dec(void) | |
3911 | { | |
3912 | static_key_slow_dec(&__cfs_bandwidth_used); | |
029632fb PZ |
3913 | } |
3914 | #else /* HAVE_JUMP_LABEL */ | |
3915 | static bool cfs_bandwidth_used(void) | |
3916 | { | |
3917 | return true; | |
3918 | } | |
3919 | ||
1ee14e6c BS |
3920 | void cfs_bandwidth_usage_inc(void) {} |
3921 | void cfs_bandwidth_usage_dec(void) {} | |
029632fb PZ |
3922 | #endif /* HAVE_JUMP_LABEL */ |
3923 | ||
ab84d31e PT |
3924 | /* |
3925 | * default period for cfs group bandwidth. | |
3926 | * default: 0.1s, units: nanoseconds | |
3927 | */ | |
3928 | static inline u64 default_cfs_period(void) | |
3929 | { | |
3930 | return 100000000ULL; | |
3931 | } | |
ec12cb7f PT |
3932 | |
3933 | static inline u64 sched_cfs_bandwidth_slice(void) | |
3934 | { | |
3935 | return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC; | |
3936 | } | |
3937 | ||
a9cf55b2 PT |
3938 | /* |
3939 | * Replenish runtime according to assigned quota and update expiration time. | |
3940 | * We use sched_clock_cpu directly instead of rq->clock to avoid adding | |
3941 | * additional synchronization around rq->lock. | |
3942 | * | |
3943 | * requires cfs_b->lock | |
3944 | */ | |
029632fb | 3945 | void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b) |
a9cf55b2 PT |
3946 | { |
3947 | u64 now; | |
3948 | ||
3949 | if (cfs_b->quota == RUNTIME_INF) | |
3950 | return; | |
3951 | ||
3952 | now = sched_clock_cpu(smp_processor_id()); | |
3953 | cfs_b->runtime = cfs_b->quota; | |
3954 | cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period); | |
3955 | } | |
3956 | ||
029632fb PZ |
3957 | static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
3958 | { | |
3959 | return &tg->cfs_bandwidth; | |
3960 | } | |
3961 | ||
f1b17280 PT |
3962 | /* rq->task_clock normalized against any time this cfs_rq has spent throttled */ |
3963 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) | |
3964 | { | |
3965 | if (unlikely(cfs_rq->throttle_count)) | |
1a99ae3f | 3966 | return cfs_rq->throttled_clock_task - cfs_rq->throttled_clock_task_time; |
f1b17280 | 3967 | |
78becc27 | 3968 | return rq_clock_task(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time; |
f1b17280 PT |
3969 | } |
3970 | ||
85dac906 PT |
3971 | /* returns 0 on failure to allocate runtime */ |
3972 | static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
ec12cb7f PT |
3973 | { |
3974 | struct task_group *tg = cfs_rq->tg; | |
3975 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg); | |
a9cf55b2 | 3976 | u64 amount = 0, min_amount, expires; |
ec12cb7f PT |
3977 | |
3978 | /* note: this is a positive sum as runtime_remaining <= 0 */ | |
3979 | min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining; | |
3980 | ||
3981 | raw_spin_lock(&cfs_b->lock); | |
3982 | if (cfs_b->quota == RUNTIME_INF) | |
3983 | amount = min_amount; | |
58088ad0 | 3984 | else { |
77a4d1a1 | 3985 | start_cfs_bandwidth(cfs_b); |
58088ad0 PT |
3986 | |
3987 | if (cfs_b->runtime > 0) { | |
3988 | amount = min(cfs_b->runtime, min_amount); | |
3989 | cfs_b->runtime -= amount; | |
3990 | cfs_b->idle = 0; | |
3991 | } | |
ec12cb7f | 3992 | } |
a9cf55b2 | 3993 | expires = cfs_b->runtime_expires; |
ec12cb7f PT |
3994 | raw_spin_unlock(&cfs_b->lock); |
3995 | ||
3996 | cfs_rq->runtime_remaining += amount; | |
a9cf55b2 PT |
3997 | /* |
3998 | * we may have advanced our local expiration to account for allowed | |
3999 | * spread between our sched_clock and the one on which runtime was | |
4000 | * issued. | |
4001 | */ | |
4002 | if ((s64)(expires - cfs_rq->runtime_expires) > 0) | |
4003 | cfs_rq->runtime_expires = expires; | |
85dac906 PT |
4004 | |
4005 | return cfs_rq->runtime_remaining > 0; | |
ec12cb7f PT |
4006 | } |
4007 | ||
a9cf55b2 PT |
4008 | /* |
4009 | * Note: This depends on the synchronization provided by sched_clock and the | |
4010 | * fact that rq->clock snapshots this value. | |
4011 | */ | |
4012 | static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
ec12cb7f | 4013 | { |
a9cf55b2 | 4014 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
a9cf55b2 PT |
4015 | |
4016 | /* if the deadline is ahead of our clock, nothing to do */ | |
78becc27 | 4017 | if (likely((s64)(rq_clock(rq_of(cfs_rq)) - cfs_rq->runtime_expires) < 0)) |
ec12cb7f PT |
4018 | return; |
4019 | ||
a9cf55b2 PT |
4020 | if (cfs_rq->runtime_remaining < 0) |
4021 | return; | |
4022 | ||
4023 | /* | |
4024 | * If the local deadline has passed we have to consider the | |
4025 | * possibility that our sched_clock is 'fast' and the global deadline | |
4026 | * has not truly expired. | |
4027 | * | |
4028 | * Fortunately we can check determine whether this the case by checking | |
51f2176d BS |
4029 | * whether the global deadline has advanced. It is valid to compare |
4030 | * cfs_b->runtime_expires without any locks since we only care about | |
4031 | * exact equality, so a partial write will still work. | |
a9cf55b2 PT |
4032 | */ |
4033 | ||
51f2176d | 4034 | if (cfs_rq->runtime_expires != cfs_b->runtime_expires) { |
a9cf55b2 PT |
4035 | /* extend local deadline, drift is bounded above by 2 ticks */ |
4036 | cfs_rq->runtime_expires += TICK_NSEC; | |
4037 | } else { | |
4038 | /* global deadline is ahead, expiration has passed */ | |
4039 | cfs_rq->runtime_remaining = 0; | |
4040 | } | |
4041 | } | |
4042 | ||
9dbdb155 | 4043 | static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
a9cf55b2 PT |
4044 | { |
4045 | /* dock delta_exec before expiring quota (as it could span periods) */ | |
ec12cb7f | 4046 | cfs_rq->runtime_remaining -= delta_exec; |
a9cf55b2 PT |
4047 | expire_cfs_rq_runtime(cfs_rq); |
4048 | ||
4049 | if (likely(cfs_rq->runtime_remaining > 0)) | |
ec12cb7f PT |
4050 | return; |
4051 | ||
85dac906 PT |
4052 | /* |
4053 | * if we're unable to extend our runtime we resched so that the active | |
4054 | * hierarchy can be throttled | |
4055 | */ | |
4056 | if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr)) | |
8875125e | 4057 | resched_curr(rq_of(cfs_rq)); |
ec12cb7f PT |
4058 | } |
4059 | ||
6c16a6dc | 4060 | static __always_inline |
9dbdb155 | 4061 | void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
ec12cb7f | 4062 | { |
56f570e5 | 4063 | if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled) |
ec12cb7f PT |
4064 | return; |
4065 | ||
4066 | __account_cfs_rq_runtime(cfs_rq, delta_exec); | |
4067 | } | |
4068 | ||
85dac906 PT |
4069 | static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) |
4070 | { | |
56f570e5 | 4071 | return cfs_bandwidth_used() && cfs_rq->throttled; |
85dac906 PT |
4072 | } |
4073 | ||
64660c86 PT |
4074 | /* check whether cfs_rq, or any parent, is throttled */ |
4075 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) | |
4076 | { | |
56f570e5 | 4077 | return cfs_bandwidth_used() && cfs_rq->throttle_count; |
64660c86 PT |
4078 | } |
4079 | ||
4080 | /* | |
4081 | * Ensure that neither of the group entities corresponding to src_cpu or | |
4082 | * dest_cpu are members of a throttled hierarchy when performing group | |
4083 | * load-balance operations. | |
4084 | */ | |
4085 | static inline int throttled_lb_pair(struct task_group *tg, | |
4086 | int src_cpu, int dest_cpu) | |
4087 | { | |
4088 | struct cfs_rq *src_cfs_rq, *dest_cfs_rq; | |
4089 | ||
4090 | src_cfs_rq = tg->cfs_rq[src_cpu]; | |
4091 | dest_cfs_rq = tg->cfs_rq[dest_cpu]; | |
4092 | ||
4093 | return throttled_hierarchy(src_cfs_rq) || | |
4094 | throttled_hierarchy(dest_cfs_rq); | |
4095 | } | |
4096 | ||
4097 | /* updated child weight may affect parent so we have to do this bottom up */ | |
4098 | static int tg_unthrottle_up(struct task_group *tg, void *data) | |
4099 | { | |
4100 | struct rq *rq = data; | |
4101 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
4102 | ||
4103 | cfs_rq->throttle_count--; | |
64660c86 | 4104 | if (!cfs_rq->throttle_count) { |
f1b17280 | 4105 | /* adjust cfs_rq_clock_task() */ |
78becc27 | 4106 | cfs_rq->throttled_clock_task_time += rq_clock_task(rq) - |
f1b17280 | 4107 | cfs_rq->throttled_clock_task; |
64660c86 | 4108 | } |
64660c86 PT |
4109 | |
4110 | return 0; | |
4111 | } | |
4112 | ||
4113 | static int tg_throttle_down(struct task_group *tg, void *data) | |
4114 | { | |
4115 | struct rq *rq = data; | |
4116 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
4117 | ||
82958366 PT |
4118 | /* group is entering throttled state, stop time */ |
4119 | if (!cfs_rq->throttle_count) | |
78becc27 | 4120 | cfs_rq->throttled_clock_task = rq_clock_task(rq); |
64660c86 PT |
4121 | cfs_rq->throttle_count++; |
4122 | ||
4123 | return 0; | |
4124 | } | |
4125 | ||
d3d9dc33 | 4126 | static void throttle_cfs_rq(struct cfs_rq *cfs_rq) |
85dac906 PT |
4127 | { |
4128 | struct rq *rq = rq_of(cfs_rq); | |
4129 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
4130 | struct sched_entity *se; | |
4131 | long task_delta, dequeue = 1; | |
77a4d1a1 | 4132 | bool empty; |
85dac906 PT |
4133 | |
4134 | se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; | |
4135 | ||
f1b17280 | 4136 | /* freeze hierarchy runnable averages while throttled */ |
64660c86 PT |
4137 | rcu_read_lock(); |
4138 | walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq); | |
4139 | rcu_read_unlock(); | |
85dac906 PT |
4140 | |
4141 | task_delta = cfs_rq->h_nr_running; | |
4142 | for_each_sched_entity(se) { | |
4143 | struct cfs_rq *qcfs_rq = cfs_rq_of(se); | |
4144 | /* throttled entity or throttle-on-deactivate */ | |
4145 | if (!se->on_rq) | |
4146 | break; | |
4147 | ||
4148 | if (dequeue) | |
4149 | dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP); | |
4150 | qcfs_rq->h_nr_running -= task_delta; | |
4151 | ||
4152 | if (qcfs_rq->load.weight) | |
4153 | dequeue = 0; | |
4154 | } | |
4155 | ||
4156 | if (!se) | |
72465447 | 4157 | sub_nr_running(rq, task_delta); |
85dac906 PT |
4158 | |
4159 | cfs_rq->throttled = 1; | |
78becc27 | 4160 | cfs_rq->throttled_clock = rq_clock(rq); |
85dac906 | 4161 | raw_spin_lock(&cfs_b->lock); |
d49db342 | 4162 | empty = list_empty(&cfs_b->throttled_cfs_rq); |
77a4d1a1 | 4163 | |
c06f04c7 BS |
4164 | /* |
4165 | * Add to the _head_ of the list, so that an already-started | |
4166 | * distribute_cfs_runtime will not see us | |
4167 | */ | |
4168 | list_add_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); | |
77a4d1a1 PZ |
4169 | |
4170 | /* | |
4171 | * If we're the first throttled task, make sure the bandwidth | |
4172 | * timer is running. | |
4173 | */ | |
4174 | if (empty) | |
4175 | start_cfs_bandwidth(cfs_b); | |
4176 | ||
85dac906 PT |
4177 | raw_spin_unlock(&cfs_b->lock); |
4178 | } | |
4179 | ||
029632fb | 4180 | void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) |
671fd9da PT |
4181 | { |
4182 | struct rq *rq = rq_of(cfs_rq); | |
4183 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
4184 | struct sched_entity *se; | |
4185 | int enqueue = 1; | |
4186 | long task_delta; | |
4187 | ||
22b958d8 | 4188 | se = cfs_rq->tg->se[cpu_of(rq)]; |
671fd9da PT |
4189 | |
4190 | cfs_rq->throttled = 0; | |
1a55af2e FW |
4191 | |
4192 | update_rq_clock(rq); | |
4193 | ||
671fd9da | 4194 | raw_spin_lock(&cfs_b->lock); |
78becc27 | 4195 | cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock; |
671fd9da PT |
4196 | list_del_rcu(&cfs_rq->throttled_list); |
4197 | raw_spin_unlock(&cfs_b->lock); | |
4198 | ||
64660c86 PT |
4199 | /* update hierarchical throttle state */ |
4200 | walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq); | |
4201 | ||
671fd9da PT |
4202 | if (!cfs_rq->load.weight) |
4203 | return; | |
4204 | ||
4205 | task_delta = cfs_rq->h_nr_running; | |
4206 | for_each_sched_entity(se) { | |
4207 | if (se->on_rq) | |
4208 | enqueue = 0; | |
4209 | ||
4210 | cfs_rq = cfs_rq_of(se); | |
4211 | if (enqueue) | |
4212 | enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); | |
4213 | cfs_rq->h_nr_running += task_delta; | |
4214 | ||
4215 | if (cfs_rq_throttled(cfs_rq)) | |
4216 | break; | |
4217 | } | |
4218 | ||
4219 | if (!se) | |
72465447 | 4220 | add_nr_running(rq, task_delta); |
671fd9da PT |
4221 | |
4222 | /* determine whether we need to wake up potentially idle cpu */ | |
4223 | if (rq->curr == rq->idle && rq->cfs.nr_running) | |
8875125e | 4224 | resched_curr(rq); |
671fd9da PT |
4225 | } |
4226 | ||
4227 | static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, | |
4228 | u64 remaining, u64 expires) | |
4229 | { | |
4230 | struct cfs_rq *cfs_rq; | |
c06f04c7 BS |
4231 | u64 runtime; |
4232 | u64 starting_runtime = remaining; | |
671fd9da PT |
4233 | |
4234 | rcu_read_lock(); | |
4235 | list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq, | |
4236 | throttled_list) { | |
4237 | struct rq *rq = rq_of(cfs_rq); | |
4238 | ||
4239 | raw_spin_lock(&rq->lock); | |
4240 | if (!cfs_rq_throttled(cfs_rq)) | |
4241 | goto next; | |
4242 | ||
4243 | runtime = -cfs_rq->runtime_remaining + 1; | |
4244 | if (runtime > remaining) | |
4245 | runtime = remaining; | |
4246 | remaining -= runtime; | |
4247 | ||
4248 | cfs_rq->runtime_remaining += runtime; | |
4249 | cfs_rq->runtime_expires = expires; | |
4250 | ||
4251 | /* we check whether we're throttled above */ | |
4252 | if (cfs_rq->runtime_remaining > 0) | |
4253 | unthrottle_cfs_rq(cfs_rq); | |
4254 | ||
4255 | next: | |
4256 | raw_spin_unlock(&rq->lock); | |
4257 | ||
4258 | if (!remaining) | |
4259 | break; | |
4260 | } | |
4261 | rcu_read_unlock(); | |
4262 | ||
c06f04c7 | 4263 | return starting_runtime - remaining; |
671fd9da PT |
4264 | } |
4265 | ||
58088ad0 PT |
4266 | /* |
4267 | * Responsible for refilling a task_group's bandwidth and unthrottling its | |
4268 | * cfs_rqs as appropriate. If there has been no activity within the last | |
4269 | * period the timer is deactivated until scheduling resumes; cfs_b->idle is | |
4270 | * used to track this state. | |
4271 | */ | |
4272 | static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) | |
4273 | { | |
671fd9da | 4274 | u64 runtime, runtime_expires; |
51f2176d | 4275 | int throttled; |
58088ad0 | 4276 | |
58088ad0 PT |
4277 | /* no need to continue the timer with no bandwidth constraint */ |
4278 | if (cfs_b->quota == RUNTIME_INF) | |
51f2176d | 4279 | goto out_deactivate; |
58088ad0 | 4280 | |
671fd9da | 4281 | throttled = !list_empty(&cfs_b->throttled_cfs_rq); |
e8da1b18 | 4282 | cfs_b->nr_periods += overrun; |
671fd9da | 4283 | |
51f2176d BS |
4284 | /* |
4285 | * idle depends on !throttled (for the case of a large deficit), and if | |
4286 | * we're going inactive then everything else can be deferred | |
4287 | */ | |
4288 | if (cfs_b->idle && !throttled) | |
4289 | goto out_deactivate; | |
a9cf55b2 PT |
4290 | |
4291 | __refill_cfs_bandwidth_runtime(cfs_b); | |
4292 | ||
671fd9da PT |
4293 | if (!throttled) { |
4294 | /* mark as potentially idle for the upcoming period */ | |
4295 | cfs_b->idle = 1; | |
51f2176d | 4296 | return 0; |
671fd9da PT |
4297 | } |
4298 | ||
e8da1b18 NR |
4299 | /* account preceding periods in which throttling occurred */ |
4300 | cfs_b->nr_throttled += overrun; | |
4301 | ||
671fd9da | 4302 | runtime_expires = cfs_b->runtime_expires; |
671fd9da PT |
4303 | |
4304 | /* | |
c06f04c7 BS |
4305 | * This check is repeated as we are holding onto the new bandwidth while |
4306 | * we unthrottle. This can potentially race with an unthrottled group | |
4307 | * trying to acquire new bandwidth from the global pool. This can result | |
4308 | * in us over-using our runtime if it is all used during this loop, but | |
4309 | * only by limited amounts in that extreme case. | |
671fd9da | 4310 | */ |
c06f04c7 BS |
4311 | while (throttled && cfs_b->runtime > 0) { |
4312 | runtime = cfs_b->runtime; | |
671fd9da PT |
4313 | raw_spin_unlock(&cfs_b->lock); |
4314 | /* we can't nest cfs_b->lock while distributing bandwidth */ | |
4315 | runtime = distribute_cfs_runtime(cfs_b, runtime, | |
4316 | runtime_expires); | |
4317 | raw_spin_lock(&cfs_b->lock); | |
4318 | ||
4319 | throttled = !list_empty(&cfs_b->throttled_cfs_rq); | |
c06f04c7 BS |
4320 | |
4321 | cfs_b->runtime -= min(runtime, cfs_b->runtime); | |
671fd9da | 4322 | } |
58088ad0 | 4323 | |
671fd9da PT |
4324 | /* |
4325 | * While we are ensured activity in the period following an | |
4326 | * unthrottle, this also covers the case in which the new bandwidth is | |
4327 | * insufficient to cover the existing bandwidth deficit. (Forcing the | |
4328 | * timer to remain active while there are any throttled entities.) | |
4329 | */ | |
4330 | cfs_b->idle = 0; | |
58088ad0 | 4331 | |
51f2176d BS |
4332 | return 0; |
4333 | ||
4334 | out_deactivate: | |
51f2176d | 4335 | return 1; |
58088ad0 | 4336 | } |
d3d9dc33 | 4337 | |
d8b4986d PT |
4338 | /* a cfs_rq won't donate quota below this amount */ |
4339 | static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC; | |
4340 | /* minimum remaining period time to redistribute slack quota */ | |
4341 | static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC; | |
4342 | /* how long we wait to gather additional slack before distributing */ | |
4343 | static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; | |
4344 | ||
db06e78c BS |
4345 | /* |
4346 | * Are we near the end of the current quota period? | |
4347 | * | |
4348 | * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the | |
4961b6e1 | 4349 | * hrtimer base being cleared by hrtimer_start. In the case of |
db06e78c BS |
4350 | * migrate_hrtimers, base is never cleared, so we are fine. |
4351 | */ | |
d8b4986d PT |
4352 | static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) |
4353 | { | |
4354 | struct hrtimer *refresh_timer = &cfs_b->period_timer; | |
4355 | u64 remaining; | |
4356 | ||
4357 | /* if the call-back is running a quota refresh is already occurring */ | |
4358 | if (hrtimer_callback_running(refresh_timer)) | |
4359 | return 1; | |
4360 | ||
4361 | /* is a quota refresh about to occur? */ | |
4362 | remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); | |
4363 | if (remaining < min_expire) | |
4364 | return 1; | |
4365 | ||
4366 | return 0; | |
4367 | } | |
4368 | ||
4369 | static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b) | |
4370 | { | |
4371 | u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration; | |
4372 | ||
4373 | /* if there's a quota refresh soon don't bother with slack */ | |
4374 | if (runtime_refresh_within(cfs_b, min_left)) | |
4375 | return; | |
4376 | ||
4cfafd30 PZ |
4377 | hrtimer_start(&cfs_b->slack_timer, |
4378 | ns_to_ktime(cfs_bandwidth_slack_period), | |
4379 | HRTIMER_MODE_REL); | |
d8b4986d PT |
4380 | } |
4381 | ||
4382 | /* we know any runtime found here is valid as update_curr() precedes return */ | |
4383 | static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
4384 | { | |
4385 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
4386 | s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime; | |
4387 | ||
4388 | if (slack_runtime <= 0) | |
4389 | return; | |
4390 | ||
4391 | raw_spin_lock(&cfs_b->lock); | |
4392 | if (cfs_b->quota != RUNTIME_INF && | |
4393 | cfs_rq->runtime_expires == cfs_b->runtime_expires) { | |
4394 | cfs_b->runtime += slack_runtime; | |
4395 | ||
4396 | /* we are under rq->lock, defer unthrottling using a timer */ | |
4397 | if (cfs_b->runtime > sched_cfs_bandwidth_slice() && | |
4398 | !list_empty(&cfs_b->throttled_cfs_rq)) | |
4399 | start_cfs_slack_bandwidth(cfs_b); | |
4400 | } | |
4401 | raw_spin_unlock(&cfs_b->lock); | |
4402 | ||
4403 | /* even if it's not valid for return we don't want to try again */ | |
4404 | cfs_rq->runtime_remaining -= slack_runtime; | |
4405 | } | |
4406 | ||
4407 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
4408 | { | |
56f570e5 PT |
4409 | if (!cfs_bandwidth_used()) |
4410 | return; | |
4411 | ||
fccfdc6f | 4412 | if (!cfs_rq->runtime_enabled || cfs_rq->nr_running) |
d8b4986d PT |
4413 | return; |
4414 | ||
4415 | __return_cfs_rq_runtime(cfs_rq); | |
4416 | } | |
4417 | ||
4418 | /* | |
4419 | * This is done with a timer (instead of inline with bandwidth return) since | |
4420 | * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs. | |
4421 | */ | |
4422 | static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) | |
4423 | { | |
4424 | u64 runtime = 0, slice = sched_cfs_bandwidth_slice(); | |
4425 | u64 expires; | |
4426 | ||
4427 | /* confirm we're still not at a refresh boundary */ | |
db06e78c BS |
4428 | raw_spin_lock(&cfs_b->lock); |
4429 | if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) { | |
4430 | raw_spin_unlock(&cfs_b->lock); | |
d8b4986d | 4431 | return; |
db06e78c | 4432 | } |
d8b4986d | 4433 | |
c06f04c7 | 4434 | if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) |
d8b4986d | 4435 | runtime = cfs_b->runtime; |
c06f04c7 | 4436 | |
d8b4986d PT |
4437 | expires = cfs_b->runtime_expires; |
4438 | raw_spin_unlock(&cfs_b->lock); | |
4439 | ||
4440 | if (!runtime) | |
4441 | return; | |
4442 | ||
4443 | runtime = distribute_cfs_runtime(cfs_b, runtime, expires); | |
4444 | ||
4445 | raw_spin_lock(&cfs_b->lock); | |
4446 | if (expires == cfs_b->runtime_expires) | |
c06f04c7 | 4447 | cfs_b->runtime -= min(runtime, cfs_b->runtime); |
d8b4986d PT |
4448 | raw_spin_unlock(&cfs_b->lock); |
4449 | } | |
4450 | ||
d3d9dc33 PT |
4451 | /* |
4452 | * When a group wakes up we want to make sure that its quota is not already | |
4453 | * expired/exceeded, otherwise it may be allowed to steal additional ticks of | |
4454 | * runtime as update_curr() throttling can not not trigger until it's on-rq. | |
4455 | */ | |
4456 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq) | |
4457 | { | |
56f570e5 PT |
4458 | if (!cfs_bandwidth_used()) |
4459 | return; | |
4460 | ||
d3d9dc33 PT |
4461 | /* an active group must be handled by the update_curr()->put() path */ |
4462 | if (!cfs_rq->runtime_enabled || cfs_rq->curr) | |
4463 | return; | |
4464 | ||
4465 | /* ensure the group is not already throttled */ | |
4466 | if (cfs_rq_throttled(cfs_rq)) | |
4467 | return; | |
4468 | ||
4469 | /* update runtime allocation */ | |
4470 | account_cfs_rq_runtime(cfs_rq, 0); | |
4471 | if (cfs_rq->runtime_remaining <= 0) | |
4472 | throttle_cfs_rq(cfs_rq); | |
4473 | } | |
4474 | ||
55e16d30 PZ |
4475 | static void sync_throttle(struct task_group *tg, int cpu) |
4476 | { | |
4477 | struct cfs_rq *pcfs_rq, *cfs_rq; | |
4478 | ||
4479 | if (!cfs_bandwidth_used()) | |
4480 | return; | |
4481 | ||
4482 | if (!tg->parent) | |
4483 | return; | |
4484 | ||
4485 | cfs_rq = tg->cfs_rq[cpu]; | |
4486 | pcfs_rq = tg->parent->cfs_rq[cpu]; | |
4487 | ||
4488 | cfs_rq->throttle_count = pcfs_rq->throttle_count; | |
b8922125 | 4489 | cfs_rq->throttled_clock_task = rq_clock_task(cpu_rq(cpu)); |
55e16d30 PZ |
4490 | } |
4491 | ||
d3d9dc33 | 4492 | /* conditionally throttle active cfs_rq's from put_prev_entity() */ |
678d5718 | 4493 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
d3d9dc33 | 4494 | { |
56f570e5 | 4495 | if (!cfs_bandwidth_used()) |
678d5718 | 4496 | return false; |
56f570e5 | 4497 | |
d3d9dc33 | 4498 | if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0)) |
678d5718 | 4499 | return false; |
d3d9dc33 PT |
4500 | |
4501 | /* | |
4502 | * it's possible for a throttled entity to be forced into a running | |
4503 | * state (e.g. set_curr_task), in this case we're finished. | |
4504 | */ | |
4505 | if (cfs_rq_throttled(cfs_rq)) | |
678d5718 | 4506 | return true; |
d3d9dc33 PT |
4507 | |
4508 | throttle_cfs_rq(cfs_rq); | |
678d5718 | 4509 | return true; |
d3d9dc33 | 4510 | } |
029632fb | 4511 | |
029632fb PZ |
4512 | static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) |
4513 | { | |
4514 | struct cfs_bandwidth *cfs_b = | |
4515 | container_of(timer, struct cfs_bandwidth, slack_timer); | |
77a4d1a1 | 4516 | |
029632fb PZ |
4517 | do_sched_cfs_slack_timer(cfs_b); |
4518 | ||
4519 | return HRTIMER_NORESTART; | |
4520 | } | |
4521 | ||
4522 | static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) | |
4523 | { | |
4524 | struct cfs_bandwidth *cfs_b = | |
4525 | container_of(timer, struct cfs_bandwidth, period_timer); | |
029632fb PZ |
4526 | int overrun; |
4527 | int idle = 0; | |
4528 | ||
51f2176d | 4529 | raw_spin_lock(&cfs_b->lock); |
029632fb | 4530 | for (;;) { |
77a4d1a1 | 4531 | overrun = hrtimer_forward_now(timer, cfs_b->period); |
029632fb PZ |
4532 | if (!overrun) |
4533 | break; | |
4534 | ||
4535 | idle = do_sched_cfs_period_timer(cfs_b, overrun); | |
4536 | } | |
4cfafd30 PZ |
4537 | if (idle) |
4538 | cfs_b->period_active = 0; | |
51f2176d | 4539 | raw_spin_unlock(&cfs_b->lock); |
029632fb PZ |
4540 | |
4541 | return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; | |
4542 | } | |
4543 | ||
4544 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) | |
4545 | { | |
4546 | raw_spin_lock_init(&cfs_b->lock); | |
4547 | cfs_b->runtime = 0; | |
4548 | cfs_b->quota = RUNTIME_INF; | |
4549 | cfs_b->period = ns_to_ktime(default_cfs_period()); | |
4550 | ||
4551 | INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq); | |
4cfafd30 | 4552 | hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED); |
029632fb PZ |
4553 | cfs_b->period_timer.function = sched_cfs_period_timer; |
4554 | hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
4555 | cfs_b->slack_timer.function = sched_cfs_slack_timer; | |
4556 | } | |
4557 | ||
4558 | static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
4559 | { | |
4560 | cfs_rq->runtime_enabled = 0; | |
4561 | INIT_LIST_HEAD(&cfs_rq->throttled_list); | |
4562 | } | |
4563 | ||
77a4d1a1 | 4564 | void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) |
029632fb | 4565 | { |
4cfafd30 | 4566 | lockdep_assert_held(&cfs_b->lock); |
029632fb | 4567 | |
4cfafd30 PZ |
4568 | if (!cfs_b->period_active) { |
4569 | cfs_b->period_active = 1; | |
4570 | hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period); | |
4571 | hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED); | |
4572 | } | |
029632fb PZ |
4573 | } |
4574 | ||
4575 | static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) | |
4576 | { | |
7f1a169b TH |
4577 | /* init_cfs_bandwidth() was not called */ |
4578 | if (!cfs_b->throttled_cfs_rq.next) | |
4579 | return; | |
4580 | ||
029632fb PZ |
4581 | hrtimer_cancel(&cfs_b->period_timer); |
4582 | hrtimer_cancel(&cfs_b->slack_timer); | |
4583 | } | |
4584 | ||
0e59bdae KT |
4585 | static void __maybe_unused update_runtime_enabled(struct rq *rq) |
4586 | { | |
4587 | struct cfs_rq *cfs_rq; | |
4588 | ||
4589 | for_each_leaf_cfs_rq(rq, cfs_rq) { | |
4590 | struct cfs_bandwidth *cfs_b = &cfs_rq->tg->cfs_bandwidth; | |
4591 | ||
4592 | raw_spin_lock(&cfs_b->lock); | |
4593 | cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; | |
4594 | raw_spin_unlock(&cfs_b->lock); | |
4595 | } | |
4596 | } | |
4597 | ||
38dc3348 | 4598 | static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq) |
029632fb PZ |
4599 | { |
4600 | struct cfs_rq *cfs_rq; | |
4601 | ||
4602 | for_each_leaf_cfs_rq(rq, cfs_rq) { | |
029632fb PZ |
4603 | if (!cfs_rq->runtime_enabled) |
4604 | continue; | |
4605 | ||
4606 | /* | |
4607 | * clock_task is not advancing so we just need to make sure | |
4608 | * there's some valid quota amount | |
4609 | */ | |
51f2176d | 4610 | cfs_rq->runtime_remaining = 1; |
0e59bdae KT |
4611 | /* |
4612 | * Offline rq is schedulable till cpu is completely disabled | |
4613 | * in take_cpu_down(), so we prevent new cfs throttling here. | |
4614 | */ | |
4615 | cfs_rq->runtime_enabled = 0; | |
4616 | ||
029632fb PZ |
4617 | if (cfs_rq_throttled(cfs_rq)) |
4618 | unthrottle_cfs_rq(cfs_rq); | |
4619 | } | |
4620 | } | |
4621 | ||
4622 | #else /* CONFIG_CFS_BANDWIDTH */ | |
f1b17280 PT |
4623 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) |
4624 | { | |
78becc27 | 4625 | return rq_clock_task(rq_of(cfs_rq)); |
f1b17280 PT |
4626 | } |
4627 | ||
9dbdb155 | 4628 | static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {} |
678d5718 | 4629 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; } |
d3d9dc33 | 4630 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} |
55e16d30 | 4631 | static inline void sync_throttle(struct task_group *tg, int cpu) {} |
6c16a6dc | 4632 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} |
85dac906 PT |
4633 | |
4634 | static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) | |
4635 | { | |
4636 | return 0; | |
4637 | } | |
64660c86 PT |
4638 | |
4639 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) | |
4640 | { | |
4641 | return 0; | |
4642 | } | |
4643 | ||
4644 | static inline int throttled_lb_pair(struct task_group *tg, | |
4645 | int src_cpu, int dest_cpu) | |
4646 | { | |
4647 | return 0; | |
4648 | } | |
029632fb PZ |
4649 | |
4650 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} | |
4651 | ||
4652 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
4653 | static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} | |
ab84d31e PT |
4654 | #endif |
4655 | ||
029632fb PZ |
4656 | static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
4657 | { | |
4658 | return NULL; | |
4659 | } | |
4660 | static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} | |
0e59bdae | 4661 | static inline void update_runtime_enabled(struct rq *rq) {} |
a4c96ae3 | 4662 | static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {} |
029632fb PZ |
4663 | |
4664 | #endif /* CONFIG_CFS_BANDWIDTH */ | |
4665 | ||
bf0f6f24 IM |
4666 | /************************************************** |
4667 | * CFS operations on tasks: | |
4668 | */ | |
4669 | ||
8f4d37ec PZ |
4670 | #ifdef CONFIG_SCHED_HRTICK |
4671 | static void hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
4672 | { | |
8f4d37ec PZ |
4673 | struct sched_entity *se = &p->se; |
4674 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
4675 | ||
9148a3a1 | 4676 | SCHED_WARN_ON(task_rq(p) != rq); |
8f4d37ec | 4677 | |
8bf46a39 | 4678 | if (rq->cfs.h_nr_running > 1) { |
8f4d37ec PZ |
4679 | u64 slice = sched_slice(cfs_rq, se); |
4680 | u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime; | |
4681 | s64 delta = slice - ran; | |
4682 | ||
4683 | if (delta < 0) { | |
4684 | if (rq->curr == p) | |
8875125e | 4685 | resched_curr(rq); |
8f4d37ec PZ |
4686 | return; |
4687 | } | |
31656519 | 4688 | hrtick_start(rq, delta); |
8f4d37ec PZ |
4689 | } |
4690 | } | |
a4c2f00f PZ |
4691 | |
4692 | /* | |
4693 | * called from enqueue/dequeue and updates the hrtick when the | |
4694 | * current task is from our class and nr_running is low enough | |
4695 | * to matter. | |
4696 | */ | |
4697 | static void hrtick_update(struct rq *rq) | |
4698 | { | |
4699 | struct task_struct *curr = rq->curr; | |
4700 | ||
b39e66ea | 4701 | if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class) |
a4c2f00f PZ |
4702 | return; |
4703 | ||
4704 | if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency) | |
4705 | hrtick_start_fair(rq, curr); | |
4706 | } | |
55e12e5e | 4707 | #else /* !CONFIG_SCHED_HRTICK */ |
8f4d37ec PZ |
4708 | static inline void |
4709 | hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
4710 | { | |
4711 | } | |
a4c2f00f PZ |
4712 | |
4713 | static inline void hrtick_update(struct rq *rq) | |
4714 | { | |
4715 | } | |
8f4d37ec PZ |
4716 | #endif |
4717 | ||
bf0f6f24 IM |
4718 | /* |
4719 | * The enqueue_task method is called before nr_running is | |
4720 | * increased. Here we update the fair scheduling stats and | |
4721 | * then put the task into the rbtree: | |
4722 | */ | |
ea87bb78 | 4723 | static void |
371fd7e7 | 4724 | enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
bf0f6f24 IM |
4725 | { |
4726 | struct cfs_rq *cfs_rq; | |
62fb1851 | 4727 | struct sched_entity *se = &p->se; |
bf0f6f24 | 4728 | |
8c34ab19 RW |
4729 | /* |
4730 | * If in_iowait is set, the code below may not trigger any cpufreq | |
4731 | * utilization updates, so do it here explicitly with the IOWAIT flag | |
4732 | * passed. | |
4733 | */ | |
4734 | if (p->in_iowait) | |
4735 | cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_IOWAIT); | |
4736 | ||
bf0f6f24 | 4737 | for_each_sched_entity(se) { |
62fb1851 | 4738 | if (se->on_rq) |
bf0f6f24 IM |
4739 | break; |
4740 | cfs_rq = cfs_rq_of(se); | |
88ec22d3 | 4741 | enqueue_entity(cfs_rq, se, flags); |
85dac906 PT |
4742 | |
4743 | /* | |
4744 | * end evaluation on encountering a throttled cfs_rq | |
4745 | * | |
4746 | * note: in the case of encountering a throttled cfs_rq we will | |
4747 | * post the final h_nr_running increment below. | |
e210bffd | 4748 | */ |
85dac906 PT |
4749 | if (cfs_rq_throttled(cfs_rq)) |
4750 | break; | |
953bfcd1 | 4751 | cfs_rq->h_nr_running++; |
85dac906 | 4752 | |
88ec22d3 | 4753 | flags = ENQUEUE_WAKEUP; |
bf0f6f24 | 4754 | } |
8f4d37ec | 4755 | |
2069dd75 | 4756 | for_each_sched_entity(se) { |
0f317143 | 4757 | cfs_rq = cfs_rq_of(se); |
953bfcd1 | 4758 | cfs_rq->h_nr_running++; |
2069dd75 | 4759 | |
85dac906 PT |
4760 | if (cfs_rq_throttled(cfs_rq)) |
4761 | break; | |
4762 | ||
d31b1a66 | 4763 | update_load_avg(se, UPDATE_TG); |
17bc14b7 | 4764 | update_cfs_shares(cfs_rq); |
2069dd75 PZ |
4765 | } |
4766 | ||
cd126afe | 4767 | if (!se) |
72465447 | 4768 | add_nr_running(rq, 1); |
cd126afe | 4769 | |
a4c2f00f | 4770 | hrtick_update(rq); |
bf0f6f24 IM |
4771 | } |
4772 | ||
2f36825b VP |
4773 | static void set_next_buddy(struct sched_entity *se); |
4774 | ||
bf0f6f24 IM |
4775 | /* |
4776 | * The dequeue_task method is called before nr_running is | |
4777 | * decreased. We remove the task from the rbtree and | |
4778 | * update the fair scheduling stats: | |
4779 | */ | |
371fd7e7 | 4780 | static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
bf0f6f24 IM |
4781 | { |
4782 | struct cfs_rq *cfs_rq; | |
62fb1851 | 4783 | struct sched_entity *se = &p->se; |
2f36825b | 4784 | int task_sleep = flags & DEQUEUE_SLEEP; |
bf0f6f24 IM |
4785 | |
4786 | for_each_sched_entity(se) { | |
4787 | cfs_rq = cfs_rq_of(se); | |
371fd7e7 | 4788 | dequeue_entity(cfs_rq, se, flags); |
85dac906 PT |
4789 | |
4790 | /* | |
4791 | * end evaluation on encountering a throttled cfs_rq | |
4792 | * | |
4793 | * note: in the case of encountering a throttled cfs_rq we will | |
4794 | * post the final h_nr_running decrement below. | |
4795 | */ | |
4796 | if (cfs_rq_throttled(cfs_rq)) | |
4797 | break; | |
953bfcd1 | 4798 | cfs_rq->h_nr_running--; |
2069dd75 | 4799 | |
bf0f6f24 | 4800 | /* Don't dequeue parent if it has other entities besides us */ |
2f36825b | 4801 | if (cfs_rq->load.weight) { |
754bd598 KK |
4802 | /* Avoid re-evaluating load for this entity: */ |
4803 | se = parent_entity(se); | |
2f36825b VP |
4804 | /* |
4805 | * Bias pick_next to pick a task from this cfs_rq, as | |
4806 | * p is sleeping when it is within its sched_slice. | |
4807 | */ | |
754bd598 KK |
4808 | if (task_sleep && se && !throttled_hierarchy(cfs_rq)) |
4809 | set_next_buddy(se); | |
bf0f6f24 | 4810 | break; |
2f36825b | 4811 | } |
371fd7e7 | 4812 | flags |= DEQUEUE_SLEEP; |
bf0f6f24 | 4813 | } |
8f4d37ec | 4814 | |
2069dd75 | 4815 | for_each_sched_entity(se) { |
0f317143 | 4816 | cfs_rq = cfs_rq_of(se); |
953bfcd1 | 4817 | cfs_rq->h_nr_running--; |
2069dd75 | 4818 | |
85dac906 PT |
4819 | if (cfs_rq_throttled(cfs_rq)) |
4820 | break; | |
4821 | ||
d31b1a66 | 4822 | update_load_avg(se, UPDATE_TG); |
17bc14b7 | 4823 | update_cfs_shares(cfs_rq); |
2069dd75 PZ |
4824 | } |
4825 | ||
cd126afe | 4826 | if (!se) |
72465447 | 4827 | sub_nr_running(rq, 1); |
cd126afe | 4828 | |
a4c2f00f | 4829 | hrtick_update(rq); |
bf0f6f24 IM |
4830 | } |
4831 | ||
e7693a36 | 4832 | #ifdef CONFIG_SMP |
10e2f1ac PZ |
4833 | |
4834 | /* Working cpumask for: load_balance, load_balance_newidle. */ | |
4835 | DEFINE_PER_CPU(cpumask_var_t, load_balance_mask); | |
4836 | DEFINE_PER_CPU(cpumask_var_t, select_idle_mask); | |
4837 | ||
9fd81dd5 | 4838 | #ifdef CONFIG_NO_HZ_COMMON |
3289bdb4 PZ |
4839 | /* |
4840 | * per rq 'load' arrray crap; XXX kill this. | |
4841 | */ | |
4842 | ||
4843 | /* | |
d937cdc5 | 4844 | * The exact cpuload calculated at every tick would be: |
3289bdb4 | 4845 | * |
d937cdc5 PZ |
4846 | * load' = (1 - 1/2^i) * load + (1/2^i) * cur_load |
4847 | * | |
4848 | * If a cpu misses updates for n ticks (as it was idle) and update gets | |
4849 | * called on the n+1-th tick when cpu may be busy, then we have: | |
4850 | * | |
4851 | * load_n = (1 - 1/2^i)^n * load_0 | |
4852 | * load_n+1 = (1 - 1/2^i) * load_n + (1/2^i) * cur_load | |
3289bdb4 PZ |
4853 | * |
4854 | * decay_load_missed() below does efficient calculation of | |
3289bdb4 | 4855 | * |
d937cdc5 PZ |
4856 | * load' = (1 - 1/2^i)^n * load |
4857 | * | |
4858 | * Because x^(n+m) := x^n * x^m we can decompose any x^n in power-of-2 factors. | |
4859 | * This allows us to precompute the above in said factors, thereby allowing the | |
4860 | * reduction of an arbitrary n in O(log_2 n) steps. (See also | |
4861 | * fixed_power_int()) | |
3289bdb4 | 4862 | * |
d937cdc5 | 4863 | * The calculation is approximated on a 128 point scale. |
3289bdb4 PZ |
4864 | */ |
4865 | #define DEGRADE_SHIFT 7 | |
d937cdc5 PZ |
4866 | |
4867 | static const u8 degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128}; | |
4868 | static const u8 degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = { | |
4869 | { 0, 0, 0, 0, 0, 0, 0, 0 }, | |
4870 | { 64, 32, 8, 0, 0, 0, 0, 0 }, | |
4871 | { 96, 72, 40, 12, 1, 0, 0, 0 }, | |
4872 | { 112, 98, 75, 43, 15, 1, 0, 0 }, | |
4873 | { 120, 112, 98, 76, 45, 16, 2, 0 } | |
4874 | }; | |
3289bdb4 PZ |
4875 | |
4876 | /* | |
4877 | * Update cpu_load for any missed ticks, due to tickless idle. The backlog | |
4878 | * would be when CPU is idle and so we just decay the old load without | |
4879 | * adding any new load. | |
4880 | */ | |
4881 | static unsigned long | |
4882 | decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) | |
4883 | { | |
4884 | int j = 0; | |
4885 | ||
4886 | if (!missed_updates) | |
4887 | return load; | |
4888 | ||
4889 | if (missed_updates >= degrade_zero_ticks[idx]) | |
4890 | return 0; | |
4891 | ||
4892 | if (idx == 1) | |
4893 | return load >> missed_updates; | |
4894 | ||
4895 | while (missed_updates) { | |
4896 | if (missed_updates % 2) | |
4897 | load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT; | |
4898 | ||
4899 | missed_updates >>= 1; | |
4900 | j++; | |
4901 | } | |
4902 | return load; | |
4903 | } | |
9fd81dd5 | 4904 | #endif /* CONFIG_NO_HZ_COMMON */ |
3289bdb4 | 4905 | |
59543275 | 4906 | /** |
cee1afce | 4907 | * __cpu_load_update - update the rq->cpu_load[] statistics |
59543275 BP |
4908 | * @this_rq: The rq to update statistics for |
4909 | * @this_load: The current load | |
4910 | * @pending_updates: The number of missed updates | |
59543275 | 4911 | * |
3289bdb4 | 4912 | * Update rq->cpu_load[] statistics. This function is usually called every |
59543275 BP |
4913 | * scheduler tick (TICK_NSEC). |
4914 | * | |
4915 | * This function computes a decaying average: | |
4916 | * | |
4917 | * load[i]' = (1 - 1/2^i) * load[i] + (1/2^i) * load | |
4918 | * | |
4919 | * Because of NOHZ it might not get called on every tick which gives need for | |
4920 | * the @pending_updates argument. | |
4921 | * | |
4922 | * load[i]_n = (1 - 1/2^i) * load[i]_n-1 + (1/2^i) * load_n-1 | |
4923 | * = A * load[i]_n-1 + B ; A := (1 - 1/2^i), B := (1/2^i) * load | |
4924 | * = A * (A * load[i]_n-2 + B) + B | |
4925 | * = A * (A * (A * load[i]_n-3 + B) + B) + B | |
4926 | * = A^3 * load[i]_n-3 + (A^2 + A + 1) * B | |
4927 | * = A^n * load[i]_0 + (A^(n-1) + A^(n-2) + ... + 1) * B | |
4928 | * = A^n * load[i]_0 + ((1 - A^n) / (1 - A)) * B | |
4929 | * = (1 - 1/2^i)^n * (load[i]_0 - load) + load | |
4930 | * | |
4931 | * In the above we've assumed load_n := load, which is true for NOHZ_FULL as | |
4932 | * any change in load would have resulted in the tick being turned back on. | |
4933 | * | |
4934 | * For regular NOHZ, this reduces to: | |
4935 | * | |
4936 | * load[i]_n = (1 - 1/2^i)^n * load[i]_0 | |
4937 | * | |
4938 | * see decay_load_misses(). For NOHZ_FULL we get to subtract and add the extra | |
1f41906a | 4939 | * term. |
3289bdb4 | 4940 | */ |
1f41906a FW |
4941 | static void cpu_load_update(struct rq *this_rq, unsigned long this_load, |
4942 | unsigned long pending_updates) | |
3289bdb4 | 4943 | { |
9fd81dd5 | 4944 | unsigned long __maybe_unused tickless_load = this_rq->cpu_load[0]; |
3289bdb4 PZ |
4945 | int i, scale; |
4946 | ||
4947 | this_rq->nr_load_updates++; | |
4948 | ||
4949 | /* Update our load: */ | |
4950 | this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */ | |
4951 | for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) { | |
4952 | unsigned long old_load, new_load; | |
4953 | ||
4954 | /* scale is effectively 1 << i now, and >> i divides by scale */ | |
4955 | ||
7400d3bb | 4956 | old_load = this_rq->cpu_load[i]; |
9fd81dd5 | 4957 | #ifdef CONFIG_NO_HZ_COMMON |
3289bdb4 | 4958 | old_load = decay_load_missed(old_load, pending_updates - 1, i); |
7400d3bb BP |
4959 | if (tickless_load) { |
4960 | old_load -= decay_load_missed(tickless_load, pending_updates - 1, i); | |
4961 | /* | |
4962 | * old_load can never be a negative value because a | |
4963 | * decayed tickless_load cannot be greater than the | |
4964 | * original tickless_load. | |
4965 | */ | |
4966 | old_load += tickless_load; | |
4967 | } | |
9fd81dd5 | 4968 | #endif |
3289bdb4 PZ |
4969 | new_load = this_load; |
4970 | /* | |
4971 | * Round up the averaging division if load is increasing. This | |
4972 | * prevents us from getting stuck on 9 if the load is 10, for | |
4973 | * example. | |
4974 | */ | |
4975 | if (new_load > old_load) | |
4976 | new_load += scale - 1; | |
4977 | ||
4978 | this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i; | |
4979 | } | |
4980 | ||
4981 | sched_avg_update(this_rq); | |
4982 | } | |
4983 | ||
7ea241af YD |
4984 | /* Used instead of source_load when we know the type == 0 */ |
4985 | static unsigned long weighted_cpuload(const int cpu) | |
4986 | { | |
4987 | return cfs_rq_runnable_load_avg(&cpu_rq(cpu)->cfs); | |
4988 | } | |
4989 | ||
3289bdb4 | 4990 | #ifdef CONFIG_NO_HZ_COMMON |
1f41906a FW |
4991 | /* |
4992 | * There is no sane way to deal with nohz on smp when using jiffies because the | |
4993 | * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading | |
4994 | * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}. | |
4995 | * | |
4996 | * Therefore we need to avoid the delta approach from the regular tick when | |
4997 | * possible since that would seriously skew the load calculation. This is why we | |
4998 | * use cpu_load_update_periodic() for CPUs out of nohz. However we'll rely on | |
4999 | * jiffies deltas for updates happening while in nohz mode (idle ticks, idle | |
5000 | * loop exit, nohz_idle_balance, nohz full exit...) | |
5001 | * | |
5002 | * This means we might still be one tick off for nohz periods. | |
5003 | */ | |
5004 | ||
5005 | static void cpu_load_update_nohz(struct rq *this_rq, | |
5006 | unsigned long curr_jiffies, | |
5007 | unsigned long load) | |
be68a682 FW |
5008 | { |
5009 | unsigned long pending_updates; | |
5010 | ||
5011 | pending_updates = curr_jiffies - this_rq->last_load_update_tick; | |
5012 | if (pending_updates) { | |
5013 | this_rq->last_load_update_tick = curr_jiffies; | |
5014 | /* | |
5015 | * In the regular NOHZ case, we were idle, this means load 0. | |
5016 | * In the NOHZ_FULL case, we were non-idle, we should consider | |
5017 | * its weighted load. | |
5018 | */ | |
1f41906a | 5019 | cpu_load_update(this_rq, load, pending_updates); |
be68a682 FW |
5020 | } |
5021 | } | |
5022 | ||
3289bdb4 PZ |
5023 | /* |
5024 | * Called from nohz_idle_balance() to update the load ratings before doing the | |
5025 | * idle balance. | |
5026 | */ | |
cee1afce | 5027 | static void cpu_load_update_idle(struct rq *this_rq) |
3289bdb4 | 5028 | { |
3289bdb4 PZ |
5029 | /* |
5030 | * bail if there's load or we're actually up-to-date. | |
5031 | */ | |
be68a682 | 5032 | if (weighted_cpuload(cpu_of(this_rq))) |
3289bdb4 PZ |
5033 | return; |
5034 | ||
1f41906a | 5035 | cpu_load_update_nohz(this_rq, READ_ONCE(jiffies), 0); |
3289bdb4 PZ |
5036 | } |
5037 | ||
5038 | /* | |
1f41906a FW |
5039 | * Record CPU load on nohz entry so we know the tickless load to account |
5040 | * on nohz exit. cpu_load[0] happens then to be updated more frequently | |
5041 | * than other cpu_load[idx] but it should be fine as cpu_load readers | |
5042 | * shouldn't rely into synchronized cpu_load[*] updates. | |
3289bdb4 | 5043 | */ |
1f41906a | 5044 | void cpu_load_update_nohz_start(void) |
3289bdb4 PZ |
5045 | { |
5046 | struct rq *this_rq = this_rq(); | |
1f41906a FW |
5047 | |
5048 | /* | |
5049 | * This is all lockless but should be fine. If weighted_cpuload changes | |
5050 | * concurrently we'll exit nohz. And cpu_load write can race with | |
5051 | * cpu_load_update_idle() but both updater would be writing the same. | |
5052 | */ | |
5053 | this_rq->cpu_load[0] = weighted_cpuload(cpu_of(this_rq)); | |
5054 | } | |
5055 | ||
5056 | /* | |
5057 | * Account the tickless load in the end of a nohz frame. | |
5058 | */ | |
5059 | void cpu_load_update_nohz_stop(void) | |
5060 | { | |
316c1608 | 5061 | unsigned long curr_jiffies = READ_ONCE(jiffies); |
1f41906a FW |
5062 | struct rq *this_rq = this_rq(); |
5063 | unsigned long load; | |
3289bdb4 PZ |
5064 | |
5065 | if (curr_jiffies == this_rq->last_load_update_tick) | |
5066 | return; | |
5067 | ||
1f41906a | 5068 | load = weighted_cpuload(cpu_of(this_rq)); |
3289bdb4 | 5069 | raw_spin_lock(&this_rq->lock); |
b52fad2d | 5070 | update_rq_clock(this_rq); |
1f41906a | 5071 | cpu_load_update_nohz(this_rq, curr_jiffies, load); |
3289bdb4 PZ |
5072 | raw_spin_unlock(&this_rq->lock); |
5073 | } | |
1f41906a FW |
5074 | #else /* !CONFIG_NO_HZ_COMMON */ |
5075 | static inline void cpu_load_update_nohz(struct rq *this_rq, | |
5076 | unsigned long curr_jiffies, | |
5077 | unsigned long load) { } | |
5078 | #endif /* CONFIG_NO_HZ_COMMON */ | |
5079 | ||
5080 | static void cpu_load_update_periodic(struct rq *this_rq, unsigned long load) | |
5081 | { | |
9fd81dd5 | 5082 | #ifdef CONFIG_NO_HZ_COMMON |
1f41906a FW |
5083 | /* See the mess around cpu_load_update_nohz(). */ |
5084 | this_rq->last_load_update_tick = READ_ONCE(jiffies); | |
9fd81dd5 | 5085 | #endif |
1f41906a FW |
5086 | cpu_load_update(this_rq, load, 1); |
5087 | } | |
3289bdb4 PZ |
5088 | |
5089 | /* | |
5090 | * Called from scheduler_tick() | |
5091 | */ | |
cee1afce | 5092 | void cpu_load_update_active(struct rq *this_rq) |
3289bdb4 | 5093 | { |
7ea241af | 5094 | unsigned long load = weighted_cpuload(cpu_of(this_rq)); |
1f41906a FW |
5095 | |
5096 | if (tick_nohz_tick_stopped()) | |
5097 | cpu_load_update_nohz(this_rq, READ_ONCE(jiffies), load); | |
5098 | else | |
5099 | cpu_load_update_periodic(this_rq, load); | |
3289bdb4 PZ |
5100 | } |
5101 | ||
029632fb PZ |
5102 | /* |
5103 | * Return a low guess at the load of a migration-source cpu weighted | |
5104 | * according to the scheduling class and "nice" value. | |
5105 | * | |
5106 | * We want to under-estimate the load of migration sources, to | |
5107 | * balance conservatively. | |
5108 | */ | |
5109 | static unsigned long source_load(int cpu, int type) | |
5110 | { | |
5111 | struct rq *rq = cpu_rq(cpu); | |
5112 | unsigned long total = weighted_cpuload(cpu); | |
5113 | ||
5114 | if (type == 0 || !sched_feat(LB_BIAS)) | |
5115 | return total; | |
5116 | ||
5117 | return min(rq->cpu_load[type-1], total); | |
5118 | } | |
5119 | ||
5120 | /* | |
5121 | * Return a high guess at the load of a migration-target cpu weighted | |
5122 | * according to the scheduling class and "nice" value. | |
5123 | */ | |
5124 | static unsigned long target_load(int cpu, int type) | |
5125 | { | |
5126 | struct rq *rq = cpu_rq(cpu); | |
5127 | unsigned long total = weighted_cpuload(cpu); | |
5128 | ||
5129 | if (type == 0 || !sched_feat(LB_BIAS)) | |
5130 | return total; | |
5131 | ||
5132 | return max(rq->cpu_load[type-1], total); | |
5133 | } | |
5134 | ||
ced549fa | 5135 | static unsigned long capacity_of(int cpu) |
029632fb | 5136 | { |
ced549fa | 5137 | return cpu_rq(cpu)->cpu_capacity; |
029632fb PZ |
5138 | } |
5139 | ||
ca6d75e6 VG |
5140 | static unsigned long capacity_orig_of(int cpu) |
5141 | { | |
5142 | return cpu_rq(cpu)->cpu_capacity_orig; | |
5143 | } | |
5144 | ||
029632fb PZ |
5145 | static unsigned long cpu_avg_load_per_task(int cpu) |
5146 | { | |
5147 | struct rq *rq = cpu_rq(cpu); | |
316c1608 | 5148 | unsigned long nr_running = READ_ONCE(rq->cfs.h_nr_running); |
7ea241af | 5149 | unsigned long load_avg = weighted_cpuload(cpu); |
029632fb PZ |
5150 | |
5151 | if (nr_running) | |
b92486cb | 5152 | return load_avg / nr_running; |
029632fb PZ |
5153 | |
5154 | return 0; | |
5155 | } | |
5156 | ||
bb3469ac | 5157 | #ifdef CONFIG_FAIR_GROUP_SCHED |
f5bfb7d9 PZ |
5158 | /* |
5159 | * effective_load() calculates the load change as seen from the root_task_group | |
5160 | * | |
5161 | * Adding load to a group doesn't make a group heavier, but can cause movement | |
5162 | * of group shares between cpus. Assuming the shares were perfectly aligned one | |
5163 | * can calculate the shift in shares. | |
cf5f0acf PZ |
5164 | * |
5165 | * Calculate the effective load difference if @wl is added (subtracted) to @tg | |
5166 | * on this @cpu and results in a total addition (subtraction) of @wg to the | |
5167 | * total group weight. | |
5168 | * | |
5169 | * Given a runqueue weight distribution (rw_i) we can compute a shares | |
5170 | * distribution (s_i) using: | |
5171 | * | |
5172 | * s_i = rw_i / \Sum rw_j (1) | |
5173 | * | |
5174 | * Suppose we have 4 CPUs and our @tg is a direct child of the root group and | |
5175 | * has 7 equal weight tasks, distributed as below (rw_i), with the resulting | |
5176 | * shares distribution (s_i): | |
5177 | * | |
5178 | * rw_i = { 2, 4, 1, 0 } | |
5179 | * s_i = { 2/7, 4/7, 1/7, 0 } | |
5180 | * | |
5181 | * As per wake_affine() we're interested in the load of two CPUs (the CPU the | |
5182 | * task used to run on and the CPU the waker is running on), we need to | |
5183 | * compute the effect of waking a task on either CPU and, in case of a sync | |
5184 | * wakeup, compute the effect of the current task going to sleep. | |
5185 | * | |
5186 | * So for a change of @wl to the local @cpu with an overall group weight change | |
5187 | * of @wl we can compute the new shares distribution (s'_i) using: | |
5188 | * | |
5189 | * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2) | |
5190 | * | |
5191 | * Suppose we're interested in CPUs 0 and 1, and want to compute the load | |
5192 | * differences in waking a task to CPU 0. The additional task changes the | |
5193 | * weight and shares distributions like: | |
5194 | * | |
5195 | * rw'_i = { 3, 4, 1, 0 } | |
5196 | * s'_i = { 3/8, 4/8, 1/8, 0 } | |
5197 | * | |
5198 | * We can then compute the difference in effective weight by using: | |
5199 | * | |
5200 | * dw_i = S * (s'_i - s_i) (3) | |
5201 | * | |
5202 | * Where 'S' is the group weight as seen by its parent. | |
5203 | * | |
5204 | * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7) | |
5205 | * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 - | |
5206 | * 4/7) times the weight of the group. | |
f5bfb7d9 | 5207 | */ |
2069dd75 | 5208 | static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
bb3469ac | 5209 | { |
4be9daaa | 5210 | struct sched_entity *se = tg->se[cpu]; |
f1d239f7 | 5211 | |
9722c2da | 5212 | if (!tg->parent) /* the trivial, non-cgroup case */ |
f1d239f7 PZ |
5213 | return wl; |
5214 | ||
4be9daaa | 5215 | for_each_sched_entity(se) { |
7dd49125 PZ |
5216 | struct cfs_rq *cfs_rq = se->my_q; |
5217 | long W, w = cfs_rq_load_avg(cfs_rq); | |
4be9daaa | 5218 | |
7dd49125 | 5219 | tg = cfs_rq->tg; |
bb3469ac | 5220 | |
cf5f0acf PZ |
5221 | /* |
5222 | * W = @wg + \Sum rw_j | |
5223 | */ | |
7dd49125 PZ |
5224 | W = wg + atomic_long_read(&tg->load_avg); |
5225 | ||
5226 | /* Ensure \Sum rw_j >= rw_i */ | |
5227 | W -= cfs_rq->tg_load_avg_contrib; | |
5228 | W += w; | |
4be9daaa | 5229 | |
cf5f0acf PZ |
5230 | /* |
5231 | * w = rw_i + @wl | |
5232 | */ | |
7dd49125 | 5233 | w += wl; |
940959e9 | 5234 | |
cf5f0acf PZ |
5235 | /* |
5236 | * wl = S * s'_i; see (2) | |
5237 | */ | |
5238 | if (W > 0 && w < W) | |
ab522e33 | 5239 | wl = (w * (long)scale_load_down(tg->shares)) / W; |
977dda7c | 5240 | else |
ab522e33 | 5241 | wl = scale_load_down(tg->shares); |
940959e9 | 5242 | |
cf5f0acf PZ |
5243 | /* |
5244 | * Per the above, wl is the new se->load.weight value; since | |
5245 | * those are clipped to [MIN_SHARES, ...) do so now. See | |
5246 | * calc_cfs_shares(). | |
5247 | */ | |
977dda7c PT |
5248 | if (wl < MIN_SHARES) |
5249 | wl = MIN_SHARES; | |
cf5f0acf PZ |
5250 | |
5251 | /* | |
5252 | * wl = dw_i = S * (s'_i - s_i); see (3) | |
5253 | */ | |
9d89c257 | 5254 | wl -= se->avg.load_avg; |
cf5f0acf PZ |
5255 | |
5256 | /* | |
5257 | * Recursively apply this logic to all parent groups to compute | |
5258 | * the final effective load change on the root group. Since | |
5259 | * only the @tg group gets extra weight, all parent groups can | |
5260 | * only redistribute existing shares. @wl is the shift in shares | |
5261 | * resulting from this level per the above. | |
5262 | */ | |
4be9daaa | 5263 | wg = 0; |
4be9daaa | 5264 | } |
bb3469ac | 5265 | |
4be9daaa | 5266 | return wl; |
bb3469ac PZ |
5267 | } |
5268 | #else | |
4be9daaa | 5269 | |
58d081b5 | 5270 | static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
4be9daaa | 5271 | { |
83378269 | 5272 | return wl; |
bb3469ac | 5273 | } |
4be9daaa | 5274 | |
bb3469ac PZ |
5275 | #endif |
5276 | ||
c58d25f3 PZ |
5277 | static void record_wakee(struct task_struct *p) |
5278 | { | |
5279 | /* | |
5280 | * Only decay a single time; tasks that have less then 1 wakeup per | |
5281 | * jiffy will not have built up many flips. | |
5282 | */ | |
5283 | if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) { | |
5284 | current->wakee_flips >>= 1; | |
5285 | current->wakee_flip_decay_ts = jiffies; | |
5286 | } | |
5287 | ||
5288 | if (current->last_wakee != p) { | |
5289 | current->last_wakee = p; | |
5290 | current->wakee_flips++; | |
5291 | } | |
5292 | } | |
5293 | ||
63b0e9ed MG |
5294 | /* |
5295 | * Detect M:N waker/wakee relationships via a switching-frequency heuristic. | |
c58d25f3 | 5296 | * |
63b0e9ed | 5297 | * A waker of many should wake a different task than the one last awakened |
c58d25f3 PZ |
5298 | * at a frequency roughly N times higher than one of its wakees. |
5299 | * | |
5300 | * In order to determine whether we should let the load spread vs consolidating | |
5301 | * to shared cache, we look for a minimum 'flip' frequency of llc_size in one | |
5302 | * partner, and a factor of lls_size higher frequency in the other. | |
5303 | * | |
5304 | * With both conditions met, we can be relatively sure that the relationship is | |
5305 | * non-monogamous, with partner count exceeding socket size. | |
5306 | * | |
5307 | * Waker/wakee being client/server, worker/dispatcher, interrupt source or | |
5308 | * whatever is irrelevant, spread criteria is apparent partner count exceeds | |
5309 | * socket size. | |
63b0e9ed | 5310 | */ |
62470419 MW |
5311 | static int wake_wide(struct task_struct *p) |
5312 | { | |
63b0e9ed MG |
5313 | unsigned int master = current->wakee_flips; |
5314 | unsigned int slave = p->wakee_flips; | |
7d9ffa89 | 5315 | int factor = this_cpu_read(sd_llc_size); |
62470419 | 5316 | |
63b0e9ed MG |
5317 | if (master < slave) |
5318 | swap(master, slave); | |
5319 | if (slave < factor || master < slave * factor) | |
5320 | return 0; | |
5321 | return 1; | |
62470419 MW |
5322 | } |
5323 | ||
772bd008 MR |
5324 | static int wake_affine(struct sched_domain *sd, struct task_struct *p, |
5325 | int prev_cpu, int sync) | |
098fb9db | 5326 | { |
e37b6a7b | 5327 | s64 this_load, load; |
bd61c98f | 5328 | s64 this_eff_load, prev_eff_load; |
772bd008 | 5329 | int idx, this_cpu; |
c88d5910 | 5330 | struct task_group *tg; |
83378269 | 5331 | unsigned long weight; |
b3137bc8 | 5332 | int balanced; |
098fb9db | 5333 | |
c88d5910 PZ |
5334 | idx = sd->wake_idx; |
5335 | this_cpu = smp_processor_id(); | |
c88d5910 PZ |
5336 | load = source_load(prev_cpu, idx); |
5337 | this_load = target_load(this_cpu, idx); | |
098fb9db | 5338 | |
b3137bc8 MG |
5339 | /* |
5340 | * If sync wakeup then subtract the (maximum possible) | |
5341 | * effect of the currently running task from the load | |
5342 | * of the current CPU: | |
5343 | */ | |
83378269 PZ |
5344 | if (sync) { |
5345 | tg = task_group(current); | |
9d89c257 | 5346 | weight = current->se.avg.load_avg; |
83378269 | 5347 | |
c88d5910 | 5348 | this_load += effective_load(tg, this_cpu, -weight, -weight); |
83378269 PZ |
5349 | load += effective_load(tg, prev_cpu, 0, -weight); |
5350 | } | |
b3137bc8 | 5351 | |
83378269 | 5352 | tg = task_group(p); |
9d89c257 | 5353 | weight = p->se.avg.load_avg; |
b3137bc8 | 5354 | |
71a29aa7 PZ |
5355 | /* |
5356 | * In low-load situations, where prev_cpu is idle and this_cpu is idle | |
c88d5910 PZ |
5357 | * due to the sync cause above having dropped this_load to 0, we'll |
5358 | * always have an imbalance, but there's really nothing you can do | |
5359 | * about that, so that's good too. | |
71a29aa7 PZ |
5360 | * |
5361 | * Otherwise check if either cpus are near enough in load to allow this | |
5362 | * task to be woken on this_cpu. | |
5363 | */ | |
bd61c98f VG |
5364 | this_eff_load = 100; |
5365 | this_eff_load *= capacity_of(prev_cpu); | |
e51fd5e2 | 5366 | |
bd61c98f VG |
5367 | prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2; |
5368 | prev_eff_load *= capacity_of(this_cpu); | |
e51fd5e2 | 5369 | |
bd61c98f | 5370 | if (this_load > 0) { |
e51fd5e2 PZ |
5371 | this_eff_load *= this_load + |
5372 | effective_load(tg, this_cpu, weight, weight); | |
5373 | ||
e51fd5e2 | 5374 | prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight); |
bd61c98f | 5375 | } |
e51fd5e2 | 5376 | |
bd61c98f | 5377 | balanced = this_eff_load <= prev_eff_load; |
098fb9db | 5378 | |
ae92882e | 5379 | schedstat_inc(p->se.statistics.nr_wakeups_affine_attempts); |
098fb9db | 5380 | |
05bfb65f VG |
5381 | if (!balanced) |
5382 | return 0; | |
098fb9db | 5383 | |
ae92882e JP |
5384 | schedstat_inc(sd->ttwu_move_affine); |
5385 | schedstat_inc(p->se.statistics.nr_wakeups_affine); | |
05bfb65f VG |
5386 | |
5387 | return 1; | |
098fb9db IM |
5388 | } |
5389 | ||
6a0b19c0 MR |
5390 | static inline int task_util(struct task_struct *p); |
5391 | static int cpu_util_wake(int cpu, struct task_struct *p); | |
5392 | ||
5393 | static unsigned long capacity_spare_wake(int cpu, struct task_struct *p) | |
5394 | { | |
5395 | return capacity_orig_of(cpu) - cpu_util_wake(cpu, p); | |
5396 | } | |
5397 | ||
aaee1203 PZ |
5398 | /* |
5399 | * find_idlest_group finds and returns the least busy CPU group within the | |
5400 | * domain. | |
5401 | */ | |
5402 | static struct sched_group * | |
78e7ed53 | 5403 | find_idlest_group(struct sched_domain *sd, struct task_struct *p, |
c44f2a02 | 5404 | int this_cpu, int sd_flag) |
e7693a36 | 5405 | { |
b3bd3de6 | 5406 | struct sched_group *idlest = NULL, *group = sd->groups; |
6a0b19c0 | 5407 | struct sched_group *most_spare_sg = NULL; |
6b94780e VG |
5408 | unsigned long min_runnable_load = ULONG_MAX, this_runnable_load = 0; |
5409 | unsigned long min_avg_load = ULONG_MAX, this_avg_load = 0; | |
6a0b19c0 | 5410 | unsigned long most_spare = 0, this_spare = 0; |
c44f2a02 | 5411 | int load_idx = sd->forkexec_idx; |
6b94780e VG |
5412 | int imbalance_scale = 100 + (sd->imbalance_pct-100)/2; |
5413 | unsigned long imbalance = scale_load_down(NICE_0_LOAD) * | |
5414 | (sd->imbalance_pct-100) / 100; | |
e7693a36 | 5415 | |
c44f2a02 VG |
5416 | if (sd_flag & SD_BALANCE_WAKE) |
5417 | load_idx = sd->wake_idx; | |
5418 | ||
aaee1203 | 5419 | do { |
6b94780e VG |
5420 | unsigned long load, avg_load, runnable_load; |
5421 | unsigned long spare_cap, max_spare_cap; | |
aaee1203 PZ |
5422 | int local_group; |
5423 | int i; | |
e7693a36 | 5424 | |
aaee1203 PZ |
5425 | /* Skip over this group if it has no CPUs allowed */ |
5426 | if (!cpumask_intersects(sched_group_cpus(group), | |
fa17b507 | 5427 | tsk_cpus_allowed(p))) |
aaee1203 PZ |
5428 | continue; |
5429 | ||
5430 | local_group = cpumask_test_cpu(this_cpu, | |
5431 | sched_group_cpus(group)); | |
5432 | ||
6a0b19c0 MR |
5433 | /* |
5434 | * Tally up the load of all CPUs in the group and find | |
5435 | * the group containing the CPU with most spare capacity. | |
5436 | */ | |
aaee1203 | 5437 | avg_load = 0; |
6b94780e | 5438 | runnable_load = 0; |
6a0b19c0 | 5439 | max_spare_cap = 0; |
aaee1203 PZ |
5440 | |
5441 | for_each_cpu(i, sched_group_cpus(group)) { | |
5442 | /* Bias balancing toward cpus of our domain */ | |
5443 | if (local_group) | |
5444 | load = source_load(i, load_idx); | |
5445 | else | |
5446 | load = target_load(i, load_idx); | |
5447 | ||
6b94780e VG |
5448 | runnable_load += load; |
5449 | ||
5450 | avg_load += cfs_rq_load_avg(&cpu_rq(i)->cfs); | |
6a0b19c0 MR |
5451 | |
5452 | spare_cap = capacity_spare_wake(i, p); | |
5453 | ||
5454 | if (spare_cap > max_spare_cap) | |
5455 | max_spare_cap = spare_cap; | |
aaee1203 PZ |
5456 | } |
5457 | ||
63b2ca30 | 5458 | /* Adjust by relative CPU capacity of the group */ |
6b94780e VG |
5459 | avg_load = (avg_load * SCHED_CAPACITY_SCALE) / |
5460 | group->sgc->capacity; | |
5461 | runnable_load = (runnable_load * SCHED_CAPACITY_SCALE) / | |
5462 | group->sgc->capacity; | |
aaee1203 PZ |
5463 | |
5464 | if (local_group) { | |
6b94780e VG |
5465 | this_runnable_load = runnable_load; |
5466 | this_avg_load = avg_load; | |
6a0b19c0 MR |
5467 | this_spare = max_spare_cap; |
5468 | } else { | |
6b94780e VG |
5469 | if (min_runnable_load > (runnable_load + imbalance)) { |
5470 | /* | |
5471 | * The runnable load is significantly smaller | |
5472 | * so we can pick this new cpu | |
5473 | */ | |
5474 | min_runnable_load = runnable_load; | |
5475 | min_avg_load = avg_load; | |
5476 | idlest = group; | |
5477 | } else if ((runnable_load < (min_runnable_load + imbalance)) && | |
5478 | (100*min_avg_load > imbalance_scale*avg_load)) { | |
5479 | /* | |
5480 | * The runnable loads are close so take the | |
5481 | * blocked load into account through avg_load. | |
5482 | */ | |
5483 | min_avg_load = avg_load; | |
6a0b19c0 MR |
5484 | idlest = group; |
5485 | } | |
5486 | ||
5487 | if (most_spare < max_spare_cap) { | |
5488 | most_spare = max_spare_cap; | |
5489 | most_spare_sg = group; | |
5490 | } | |
aaee1203 PZ |
5491 | } |
5492 | } while (group = group->next, group != sd->groups); | |
5493 | ||
6a0b19c0 MR |
5494 | /* |
5495 | * The cross-over point between using spare capacity or least load | |
5496 | * is too conservative for high utilization tasks on partially | |
5497 | * utilized systems if we require spare_capacity > task_util(p), | |
5498 | * so we allow for some task stuffing by using | |
5499 | * spare_capacity > task_util(p)/2. | |
f519a3f1 VG |
5500 | * |
5501 | * Spare capacity can't be used for fork because the utilization has | |
5502 | * not been set yet, we must first select a rq to compute the initial | |
5503 | * utilization. | |
6a0b19c0 | 5504 | */ |
f519a3f1 VG |
5505 | if (sd_flag & SD_BALANCE_FORK) |
5506 | goto skip_spare; | |
5507 | ||
6a0b19c0 | 5508 | if (this_spare > task_util(p) / 2 && |
6b94780e | 5509 | imbalance_scale*this_spare > 100*most_spare) |
6a0b19c0 | 5510 | return NULL; |
6b94780e VG |
5511 | |
5512 | if (most_spare > task_util(p) / 2) | |
6a0b19c0 MR |
5513 | return most_spare_sg; |
5514 | ||
f519a3f1 | 5515 | skip_spare: |
6b94780e VG |
5516 | if (!idlest) |
5517 | return NULL; | |
5518 | ||
5519 | if (min_runnable_load > (this_runnable_load + imbalance)) | |
aaee1203 | 5520 | return NULL; |
6b94780e VG |
5521 | |
5522 | if ((this_runnable_load < (min_runnable_load + imbalance)) && | |
5523 | (100*this_avg_load < imbalance_scale*min_avg_load)) | |
5524 | return NULL; | |
5525 | ||
aaee1203 PZ |
5526 | return idlest; |
5527 | } | |
5528 | ||
5529 | /* | |
5530 | * find_idlest_cpu - find the idlest cpu among the cpus in group. | |
5531 | */ | |
5532 | static int | |
5533 | find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) | |
5534 | { | |
5535 | unsigned long load, min_load = ULONG_MAX; | |
83a0a96a NP |
5536 | unsigned int min_exit_latency = UINT_MAX; |
5537 | u64 latest_idle_timestamp = 0; | |
5538 | int least_loaded_cpu = this_cpu; | |
5539 | int shallowest_idle_cpu = -1; | |
aaee1203 PZ |
5540 | int i; |
5541 | ||
eaecf41f MR |
5542 | /* Check if we have any choice: */ |
5543 | if (group->group_weight == 1) | |
5544 | return cpumask_first(sched_group_cpus(group)); | |
5545 | ||
aaee1203 | 5546 | /* Traverse only the allowed CPUs */ |
fa17b507 | 5547 | for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { |
83a0a96a NP |
5548 | if (idle_cpu(i)) { |
5549 | struct rq *rq = cpu_rq(i); | |
5550 | struct cpuidle_state *idle = idle_get_state(rq); | |
5551 | if (idle && idle->exit_latency < min_exit_latency) { | |
5552 | /* | |
5553 | * We give priority to a CPU whose idle state | |
5554 | * has the smallest exit latency irrespective | |
5555 | * of any idle timestamp. | |
5556 | */ | |
5557 | min_exit_latency = idle->exit_latency; | |
5558 | latest_idle_timestamp = rq->idle_stamp; | |
5559 | shallowest_idle_cpu = i; | |
5560 | } else if ((!idle || idle->exit_latency == min_exit_latency) && | |
5561 | rq->idle_stamp > latest_idle_timestamp) { | |
5562 | /* | |
5563 | * If equal or no active idle state, then | |
5564 | * the most recently idled CPU might have | |
5565 | * a warmer cache. | |
5566 | */ | |
5567 | latest_idle_timestamp = rq->idle_stamp; | |
5568 | shallowest_idle_cpu = i; | |
5569 | } | |
9f96742a | 5570 | } else if (shallowest_idle_cpu == -1) { |
83a0a96a NP |
5571 | load = weighted_cpuload(i); |
5572 | if (load < min_load || (load == min_load && i == this_cpu)) { | |
5573 | min_load = load; | |
5574 | least_loaded_cpu = i; | |
5575 | } | |
e7693a36 GH |
5576 | } |
5577 | } | |
5578 | ||
83a0a96a | 5579 | return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu; |
aaee1203 | 5580 | } |
e7693a36 | 5581 | |
a50bde51 | 5582 | /* |
10e2f1ac PZ |
5583 | * Implement a for_each_cpu() variant that starts the scan at a given cpu |
5584 | * (@start), and wraps around. | |
5585 | * | |
5586 | * This is used to scan for idle CPUs; such that not all CPUs looking for an | |
5587 | * idle CPU find the same CPU. The down-side is that tasks tend to cycle | |
5588 | * through the LLC domain. | |
5589 | * | |
5590 | * Especially tbench is found sensitive to this. | |
5591 | */ | |
5592 | ||
5593 | static int cpumask_next_wrap(int n, const struct cpumask *mask, int start, int *wrapped) | |
5594 | { | |
5595 | int next; | |
5596 | ||
5597 | again: | |
5598 | next = find_next_bit(cpumask_bits(mask), nr_cpumask_bits, n+1); | |
5599 | ||
5600 | if (*wrapped) { | |
5601 | if (next >= start) | |
5602 | return nr_cpumask_bits; | |
5603 | } else { | |
5604 | if (next >= nr_cpumask_bits) { | |
5605 | *wrapped = 1; | |
5606 | n = -1; | |
5607 | goto again; | |
5608 | } | |
5609 | } | |
5610 | ||
5611 | return next; | |
5612 | } | |
5613 | ||
5614 | #define for_each_cpu_wrap(cpu, mask, start, wrap) \ | |
5615 | for ((wrap) = 0, (cpu) = (start)-1; \ | |
5616 | (cpu) = cpumask_next_wrap((cpu), (mask), (start), &(wrap)), \ | |
5617 | (cpu) < nr_cpumask_bits; ) | |
5618 | ||
5619 | #ifdef CONFIG_SCHED_SMT | |
5620 | ||
5621 | static inline void set_idle_cores(int cpu, int val) | |
5622 | { | |
5623 | struct sched_domain_shared *sds; | |
5624 | ||
5625 | sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); | |
5626 | if (sds) | |
5627 | WRITE_ONCE(sds->has_idle_cores, val); | |
5628 | } | |
5629 | ||
5630 | static inline bool test_idle_cores(int cpu, bool def) | |
5631 | { | |
5632 | struct sched_domain_shared *sds; | |
5633 | ||
5634 | sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); | |
5635 | if (sds) | |
5636 | return READ_ONCE(sds->has_idle_cores); | |
5637 | ||
5638 | return def; | |
5639 | } | |
5640 | ||
5641 | /* | |
5642 | * Scans the local SMT mask to see if the entire core is idle, and records this | |
5643 | * information in sd_llc_shared->has_idle_cores. | |
5644 | * | |
5645 | * Since SMT siblings share all cache levels, inspecting this limited remote | |
5646 | * state should be fairly cheap. | |
5647 | */ | |
1b568f0a | 5648 | void __update_idle_core(struct rq *rq) |
10e2f1ac PZ |
5649 | { |
5650 | int core = cpu_of(rq); | |
5651 | int cpu; | |
5652 | ||
5653 | rcu_read_lock(); | |
5654 | if (test_idle_cores(core, true)) | |
5655 | goto unlock; | |
5656 | ||
5657 | for_each_cpu(cpu, cpu_smt_mask(core)) { | |
5658 | if (cpu == core) | |
5659 | continue; | |
5660 | ||
5661 | if (!idle_cpu(cpu)) | |
5662 | goto unlock; | |
5663 | } | |
5664 | ||
5665 | set_idle_cores(core, 1); | |
5666 | unlock: | |
5667 | rcu_read_unlock(); | |
5668 | } | |
5669 | ||
5670 | /* | |
5671 | * Scan the entire LLC domain for idle cores; this dynamically switches off if | |
5672 | * there are no idle cores left in the system; tracked through | |
5673 | * sd_llc->shared->has_idle_cores and enabled through update_idle_core() above. | |
5674 | */ | |
5675 | static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target) | |
5676 | { | |
5677 | struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask); | |
5678 | int core, cpu, wrap; | |
5679 | ||
1b568f0a PZ |
5680 | if (!static_branch_likely(&sched_smt_present)) |
5681 | return -1; | |
5682 | ||
10e2f1ac PZ |
5683 | if (!test_idle_cores(target, false)) |
5684 | return -1; | |
5685 | ||
5686 | cpumask_and(cpus, sched_domain_span(sd), tsk_cpus_allowed(p)); | |
5687 | ||
5688 | for_each_cpu_wrap(core, cpus, target, wrap) { | |
5689 | bool idle = true; | |
5690 | ||
5691 | for_each_cpu(cpu, cpu_smt_mask(core)) { | |
5692 | cpumask_clear_cpu(cpu, cpus); | |
5693 | if (!idle_cpu(cpu)) | |
5694 | idle = false; | |
5695 | } | |
5696 | ||
5697 | if (idle) | |
5698 | return core; | |
5699 | } | |
5700 | ||
5701 | /* | |
5702 | * Failed to find an idle core; stop looking for one. | |
5703 | */ | |
5704 | set_idle_cores(target, 0); | |
5705 | ||
5706 | return -1; | |
5707 | } | |
5708 | ||
5709 | /* | |
5710 | * Scan the local SMT mask for idle CPUs. | |
5711 | */ | |
5712 | static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target) | |
5713 | { | |
5714 | int cpu; | |
5715 | ||
1b568f0a PZ |
5716 | if (!static_branch_likely(&sched_smt_present)) |
5717 | return -1; | |
5718 | ||
10e2f1ac PZ |
5719 | for_each_cpu(cpu, cpu_smt_mask(target)) { |
5720 | if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) | |
5721 | continue; | |
5722 | if (idle_cpu(cpu)) | |
5723 | return cpu; | |
5724 | } | |
5725 | ||
5726 | return -1; | |
5727 | } | |
5728 | ||
5729 | #else /* CONFIG_SCHED_SMT */ | |
5730 | ||
5731 | static inline int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target) | |
5732 | { | |
5733 | return -1; | |
5734 | } | |
5735 | ||
5736 | static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target) | |
5737 | { | |
5738 | return -1; | |
5739 | } | |
5740 | ||
5741 | #endif /* CONFIG_SCHED_SMT */ | |
5742 | ||
5743 | /* | |
5744 | * Scan the LLC domain for idle CPUs; this is dynamically regulated by | |
5745 | * comparing the average scan cost (tracked in sd->avg_scan_cost) against the | |
5746 | * average idle time for this rq (as found in rq->avg_idle). | |
a50bde51 | 5747 | */ |
10e2f1ac PZ |
5748 | static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int target) |
5749 | { | |
9cfb38a7 WL |
5750 | struct sched_domain *this_sd; |
5751 | u64 avg_cost, avg_idle = this_rq()->avg_idle; | |
10e2f1ac PZ |
5752 | u64 time, cost; |
5753 | s64 delta; | |
5754 | int cpu, wrap; | |
5755 | ||
9cfb38a7 WL |
5756 | this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc)); |
5757 | if (!this_sd) | |
5758 | return -1; | |
5759 | ||
5760 | avg_cost = this_sd->avg_scan_cost; | |
5761 | ||
10e2f1ac PZ |
5762 | /* |
5763 | * Due to large variance we need a large fuzz factor; hackbench in | |
5764 | * particularly is sensitive here. | |
5765 | */ | |
5766 | if ((avg_idle / 512) < avg_cost) | |
5767 | return -1; | |
5768 | ||
5769 | time = local_clock(); | |
5770 | ||
5771 | for_each_cpu_wrap(cpu, sched_domain_span(sd), target, wrap) { | |
5772 | if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) | |
5773 | continue; | |
5774 | if (idle_cpu(cpu)) | |
5775 | break; | |
5776 | } | |
5777 | ||
5778 | time = local_clock() - time; | |
5779 | cost = this_sd->avg_scan_cost; | |
5780 | delta = (s64)(time - cost) / 8; | |
5781 | this_sd->avg_scan_cost += delta; | |
5782 | ||
5783 | return cpu; | |
5784 | } | |
5785 | ||
5786 | /* | |
5787 | * Try and locate an idle core/thread in the LLC cache domain. | |
a50bde51 | 5788 | */ |
772bd008 | 5789 | static int select_idle_sibling(struct task_struct *p, int prev, int target) |
a50bde51 | 5790 | { |
99bd5e2f | 5791 | struct sched_domain *sd; |
10e2f1ac | 5792 | int i; |
a50bde51 | 5793 | |
e0a79f52 MG |
5794 | if (idle_cpu(target)) |
5795 | return target; | |
99bd5e2f SS |
5796 | |
5797 | /* | |
10e2f1ac | 5798 | * If the previous cpu is cache affine and idle, don't be stupid. |
99bd5e2f | 5799 | */ |
772bd008 MR |
5800 | if (prev != target && cpus_share_cache(prev, target) && idle_cpu(prev)) |
5801 | return prev; | |
a50bde51 | 5802 | |
518cd623 | 5803 | sd = rcu_dereference(per_cpu(sd_llc, target)); |
10e2f1ac PZ |
5804 | if (!sd) |
5805 | return target; | |
772bd008 | 5806 | |
10e2f1ac PZ |
5807 | i = select_idle_core(p, sd, target); |
5808 | if ((unsigned)i < nr_cpumask_bits) | |
5809 | return i; | |
37407ea7 | 5810 | |
10e2f1ac PZ |
5811 | i = select_idle_cpu(p, sd, target); |
5812 | if ((unsigned)i < nr_cpumask_bits) | |
5813 | return i; | |
5814 | ||
5815 | i = select_idle_smt(p, sd, target); | |
5816 | if ((unsigned)i < nr_cpumask_bits) | |
5817 | return i; | |
970e1789 | 5818 | |
a50bde51 PZ |
5819 | return target; |
5820 | } | |
231678b7 | 5821 | |
8bb5b00c | 5822 | /* |
9e91d61d | 5823 | * cpu_util returns the amount of capacity of a CPU that is used by CFS |
8bb5b00c | 5824 | * tasks. The unit of the return value must be the one of capacity so we can |
9e91d61d DE |
5825 | * compare the utilization with the capacity of the CPU that is available for |
5826 | * CFS task (ie cpu_capacity). | |
231678b7 DE |
5827 | * |
5828 | * cfs_rq.avg.util_avg is the sum of running time of runnable tasks plus the | |
5829 | * recent utilization of currently non-runnable tasks on a CPU. It represents | |
5830 | * the amount of utilization of a CPU in the range [0..capacity_orig] where | |
5831 | * capacity_orig is the cpu_capacity available at the highest frequency | |
5832 | * (arch_scale_freq_capacity()). | |
5833 | * The utilization of a CPU converges towards a sum equal to or less than the | |
5834 | * current capacity (capacity_curr <= capacity_orig) of the CPU because it is | |
5835 | * the running time on this CPU scaled by capacity_curr. | |
5836 | * | |
5837 | * Nevertheless, cfs_rq.avg.util_avg can be higher than capacity_curr or even | |
5838 | * higher than capacity_orig because of unfortunate rounding in | |
5839 | * cfs.avg.util_avg or just after migrating tasks and new task wakeups until | |
5840 | * the average stabilizes with the new running time. We need to check that the | |
5841 | * utilization stays within the range of [0..capacity_orig] and cap it if | |
5842 | * necessary. Without utilization capping, a group could be seen as overloaded | |
5843 | * (CPU0 utilization at 121% + CPU1 utilization at 80%) whereas CPU1 has 20% of | |
5844 | * available capacity. We allow utilization to overshoot capacity_curr (but not | |
5845 | * capacity_orig) as it useful for predicting the capacity required after task | |
5846 | * migrations (scheduler-driven DVFS). | |
8bb5b00c | 5847 | */ |
9e91d61d | 5848 | static int cpu_util(int cpu) |
8bb5b00c | 5849 | { |
9e91d61d | 5850 | unsigned long util = cpu_rq(cpu)->cfs.avg.util_avg; |
8bb5b00c VG |
5851 | unsigned long capacity = capacity_orig_of(cpu); |
5852 | ||
231678b7 | 5853 | return (util >= capacity) ? capacity : util; |
8bb5b00c | 5854 | } |
a50bde51 | 5855 | |
3273163c MR |
5856 | static inline int task_util(struct task_struct *p) |
5857 | { | |
5858 | return p->se.avg.util_avg; | |
5859 | } | |
5860 | ||
104cb16d MR |
5861 | /* |
5862 | * cpu_util_wake: Compute cpu utilization with any contributions from | |
5863 | * the waking task p removed. | |
5864 | */ | |
5865 | static int cpu_util_wake(int cpu, struct task_struct *p) | |
5866 | { | |
5867 | unsigned long util, capacity; | |
5868 | ||
5869 | /* Task has no contribution or is new */ | |
5870 | if (cpu != task_cpu(p) || !p->se.avg.last_update_time) | |
5871 | return cpu_util(cpu); | |
5872 | ||
5873 | capacity = capacity_orig_of(cpu); | |
5874 | util = max_t(long, cpu_rq(cpu)->cfs.avg.util_avg - task_util(p), 0); | |
5875 | ||
5876 | return (util >= capacity) ? capacity : util; | |
5877 | } | |
5878 | ||
3273163c MR |
5879 | /* |
5880 | * Disable WAKE_AFFINE in the case where task @p doesn't fit in the | |
5881 | * capacity of either the waking CPU @cpu or the previous CPU @prev_cpu. | |
5882 | * | |
5883 | * In that case WAKE_AFFINE doesn't make sense and we'll let | |
5884 | * BALANCE_WAKE sort things out. | |
5885 | */ | |
5886 | static int wake_cap(struct task_struct *p, int cpu, int prev_cpu) | |
5887 | { | |
5888 | long min_cap, max_cap; | |
5889 | ||
5890 | min_cap = min(capacity_orig_of(prev_cpu), capacity_orig_of(cpu)); | |
5891 | max_cap = cpu_rq(cpu)->rd->max_cpu_capacity; | |
5892 | ||
5893 | /* Minimum capacity is close to max, no need to abort wake_affine */ | |
5894 | if (max_cap - min_cap < max_cap >> 3) | |
5895 | return 0; | |
5896 | ||
104cb16d MR |
5897 | /* Bring task utilization in sync with prev_cpu */ |
5898 | sync_entity_load_avg(&p->se); | |
5899 | ||
3273163c MR |
5900 | return min_cap * 1024 < task_util(p) * capacity_margin; |
5901 | } | |
5902 | ||
aaee1203 | 5903 | /* |
de91b9cb MR |
5904 | * select_task_rq_fair: Select target runqueue for the waking task in domains |
5905 | * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE, | |
5906 | * SD_BALANCE_FORK, or SD_BALANCE_EXEC. | |
aaee1203 | 5907 | * |
de91b9cb MR |
5908 | * Balances load by selecting the idlest cpu in the idlest group, or under |
5909 | * certain conditions an idle sibling cpu if the domain has SD_WAKE_AFFINE set. | |
aaee1203 | 5910 | * |
de91b9cb | 5911 | * Returns the target cpu number. |
aaee1203 PZ |
5912 | * |
5913 | * preempt must be disabled. | |
5914 | */ | |
0017d735 | 5915 | static int |
ac66f547 | 5916 | select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags) |
aaee1203 | 5917 | { |
29cd8bae | 5918 | struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; |
c88d5910 | 5919 | int cpu = smp_processor_id(); |
63b0e9ed | 5920 | int new_cpu = prev_cpu; |
99bd5e2f | 5921 | int want_affine = 0; |
5158f4e4 | 5922 | int sync = wake_flags & WF_SYNC; |
c88d5910 | 5923 | |
c58d25f3 PZ |
5924 | if (sd_flag & SD_BALANCE_WAKE) { |
5925 | record_wakee(p); | |
3273163c MR |
5926 | want_affine = !wake_wide(p) && !wake_cap(p, cpu, prev_cpu) |
5927 | && cpumask_test_cpu(cpu, tsk_cpus_allowed(p)); | |
c58d25f3 | 5928 | } |
aaee1203 | 5929 | |
dce840a0 | 5930 | rcu_read_lock(); |
aaee1203 | 5931 | for_each_domain(cpu, tmp) { |
e4f42888 | 5932 | if (!(tmp->flags & SD_LOAD_BALANCE)) |
63b0e9ed | 5933 | break; |
e4f42888 | 5934 | |
fe3bcfe1 | 5935 | /* |
99bd5e2f SS |
5936 | * If both cpu and prev_cpu are part of this domain, |
5937 | * cpu is a valid SD_WAKE_AFFINE target. | |
fe3bcfe1 | 5938 | */ |
99bd5e2f SS |
5939 | if (want_affine && (tmp->flags & SD_WAKE_AFFINE) && |
5940 | cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) { | |
5941 | affine_sd = tmp; | |
29cd8bae | 5942 | break; |
f03542a7 | 5943 | } |
29cd8bae | 5944 | |
f03542a7 | 5945 | if (tmp->flags & sd_flag) |
29cd8bae | 5946 | sd = tmp; |
63b0e9ed MG |
5947 | else if (!want_affine) |
5948 | break; | |
29cd8bae PZ |
5949 | } |
5950 | ||
63b0e9ed MG |
5951 | if (affine_sd) { |
5952 | sd = NULL; /* Prefer wake_affine over balance flags */ | |
772bd008 | 5953 | if (cpu != prev_cpu && wake_affine(affine_sd, p, prev_cpu, sync)) |
63b0e9ed | 5954 | new_cpu = cpu; |
8b911acd | 5955 | } |
e7693a36 | 5956 | |
63b0e9ed MG |
5957 | if (!sd) { |
5958 | if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */ | |
772bd008 | 5959 | new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); |
63b0e9ed MG |
5960 | |
5961 | } else while (sd) { | |
aaee1203 | 5962 | struct sched_group *group; |
c88d5910 | 5963 | int weight; |
098fb9db | 5964 | |
0763a660 | 5965 | if (!(sd->flags & sd_flag)) { |
aaee1203 PZ |
5966 | sd = sd->child; |
5967 | continue; | |
5968 | } | |
098fb9db | 5969 | |
c44f2a02 | 5970 | group = find_idlest_group(sd, p, cpu, sd_flag); |
aaee1203 PZ |
5971 | if (!group) { |
5972 | sd = sd->child; | |
5973 | continue; | |
5974 | } | |
4ae7d5ce | 5975 | |
d7c33c49 | 5976 | new_cpu = find_idlest_cpu(group, p, cpu); |
aaee1203 PZ |
5977 | if (new_cpu == -1 || new_cpu == cpu) { |
5978 | /* Now try balancing at a lower domain level of cpu */ | |
5979 | sd = sd->child; | |
5980 | continue; | |
e7693a36 | 5981 | } |
aaee1203 PZ |
5982 | |
5983 | /* Now try balancing at a lower domain level of new_cpu */ | |
5984 | cpu = new_cpu; | |
669c55e9 | 5985 | weight = sd->span_weight; |
aaee1203 PZ |
5986 | sd = NULL; |
5987 | for_each_domain(cpu, tmp) { | |
669c55e9 | 5988 | if (weight <= tmp->span_weight) |
aaee1203 | 5989 | break; |
0763a660 | 5990 | if (tmp->flags & sd_flag) |
aaee1203 PZ |
5991 | sd = tmp; |
5992 | } | |
5993 | /* while loop will break here if sd == NULL */ | |
e7693a36 | 5994 | } |
dce840a0 | 5995 | rcu_read_unlock(); |
e7693a36 | 5996 | |
c88d5910 | 5997 | return new_cpu; |
e7693a36 | 5998 | } |
0a74bef8 PT |
5999 | |
6000 | /* | |
6001 | * Called immediately before a task is migrated to a new cpu; task_cpu(p) and | |
6002 | * cfs_rq_of(p) references at time of call are still valid and identify the | |
525628c7 | 6003 | * previous cpu. The caller guarantees p->pi_lock or task_rq(p)->lock is held. |
0a74bef8 | 6004 | */ |
5a4fd036 | 6005 | static void migrate_task_rq_fair(struct task_struct *p) |
0a74bef8 | 6006 | { |
59efa0ba PZ |
6007 | /* |
6008 | * As blocked tasks retain absolute vruntime the migration needs to | |
6009 | * deal with this by subtracting the old and adding the new | |
6010 | * min_vruntime -- the latter is done by enqueue_entity() when placing | |
6011 | * the task on the new runqueue. | |
6012 | */ | |
6013 | if (p->state == TASK_WAKING) { | |
6014 | struct sched_entity *se = &p->se; | |
6015 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
6016 | u64 min_vruntime; | |
6017 | ||
6018 | #ifndef CONFIG_64BIT | |
6019 | u64 min_vruntime_copy; | |
6020 | ||
6021 | do { | |
6022 | min_vruntime_copy = cfs_rq->min_vruntime_copy; | |
6023 | smp_rmb(); | |
6024 | min_vruntime = cfs_rq->min_vruntime; | |
6025 | } while (min_vruntime != min_vruntime_copy); | |
6026 | #else | |
6027 | min_vruntime = cfs_rq->min_vruntime; | |
6028 | #endif | |
6029 | ||
6030 | se->vruntime -= min_vruntime; | |
6031 | } | |
6032 | ||
aff3e498 | 6033 | /* |
9d89c257 YD |
6034 | * We are supposed to update the task to "current" time, then its up to date |
6035 | * and ready to go to new CPU/cfs_rq. But we have difficulty in getting | |
6036 | * what current time is, so simply throw away the out-of-date time. This | |
6037 | * will result in the wakee task is less decayed, but giving the wakee more | |
6038 | * load sounds not bad. | |
aff3e498 | 6039 | */ |
9d89c257 YD |
6040 | remove_entity_load_avg(&p->se); |
6041 | ||
6042 | /* Tell new CPU we are migrated */ | |
6043 | p->se.avg.last_update_time = 0; | |
3944a927 BS |
6044 | |
6045 | /* We have migrated, no longer consider this task hot */ | |
9d89c257 | 6046 | p->se.exec_start = 0; |
0a74bef8 | 6047 | } |
12695578 YD |
6048 | |
6049 | static void task_dead_fair(struct task_struct *p) | |
6050 | { | |
6051 | remove_entity_load_avg(&p->se); | |
6052 | } | |
e7693a36 GH |
6053 | #endif /* CONFIG_SMP */ |
6054 | ||
e52fb7c0 PZ |
6055 | static unsigned long |
6056 | wakeup_gran(struct sched_entity *curr, struct sched_entity *se) | |
0bbd3336 PZ |
6057 | { |
6058 | unsigned long gran = sysctl_sched_wakeup_granularity; | |
6059 | ||
6060 | /* | |
e52fb7c0 PZ |
6061 | * Since its curr running now, convert the gran from real-time |
6062 | * to virtual-time in his units. | |
13814d42 MG |
6063 | * |
6064 | * By using 'se' instead of 'curr' we penalize light tasks, so | |
6065 | * they get preempted easier. That is, if 'se' < 'curr' then | |
6066 | * the resulting gran will be larger, therefore penalizing the | |
6067 | * lighter, if otoh 'se' > 'curr' then the resulting gran will | |
6068 | * be smaller, again penalizing the lighter task. | |
6069 | * | |
6070 | * This is especially important for buddies when the leftmost | |
6071 | * task is higher priority than the buddy. | |
0bbd3336 | 6072 | */ |
f4ad9bd2 | 6073 | return calc_delta_fair(gran, se); |
0bbd3336 PZ |
6074 | } |
6075 | ||
464b7527 PZ |
6076 | /* |
6077 | * Should 'se' preempt 'curr'. | |
6078 | * | |
6079 | * |s1 | |
6080 | * |s2 | |
6081 | * |s3 | |
6082 | * g | |
6083 | * |<--->|c | |
6084 | * | |
6085 | * w(c, s1) = -1 | |
6086 | * w(c, s2) = 0 | |
6087 | * w(c, s3) = 1 | |
6088 | * | |
6089 | */ | |
6090 | static int | |
6091 | wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) | |
6092 | { | |
6093 | s64 gran, vdiff = curr->vruntime - se->vruntime; | |
6094 | ||
6095 | if (vdiff <= 0) | |
6096 | return -1; | |
6097 | ||
e52fb7c0 | 6098 | gran = wakeup_gran(curr, se); |
464b7527 PZ |
6099 | if (vdiff > gran) |
6100 | return 1; | |
6101 | ||
6102 | return 0; | |
6103 | } | |
6104 | ||
02479099 PZ |
6105 | static void set_last_buddy(struct sched_entity *se) |
6106 | { | |
69c80f3e VP |
6107 | if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
6108 | return; | |
6109 | ||
6110 | for_each_sched_entity(se) | |
6111 | cfs_rq_of(se)->last = se; | |
02479099 PZ |
6112 | } |
6113 | ||
6114 | static void set_next_buddy(struct sched_entity *se) | |
6115 | { | |
69c80f3e VP |
6116 | if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
6117 | return; | |
6118 | ||
6119 | for_each_sched_entity(se) | |
6120 | cfs_rq_of(se)->next = se; | |
02479099 PZ |
6121 | } |
6122 | ||
ac53db59 RR |
6123 | static void set_skip_buddy(struct sched_entity *se) |
6124 | { | |
69c80f3e VP |
6125 | for_each_sched_entity(se) |
6126 | cfs_rq_of(se)->skip = se; | |
ac53db59 RR |
6127 | } |
6128 | ||
bf0f6f24 IM |
6129 | /* |
6130 | * Preempt the current task with a newly woken task if needed: | |
6131 | */ | |
5a9b86f6 | 6132 | static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) |
bf0f6f24 IM |
6133 | { |
6134 | struct task_struct *curr = rq->curr; | |
8651a86c | 6135 | struct sched_entity *se = &curr->se, *pse = &p->se; |
03e89e45 | 6136 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
f685ceac | 6137 | int scale = cfs_rq->nr_running >= sched_nr_latency; |
2f36825b | 6138 | int next_buddy_marked = 0; |
bf0f6f24 | 6139 | |
4ae7d5ce IM |
6140 | if (unlikely(se == pse)) |
6141 | return; | |
6142 | ||
5238cdd3 | 6143 | /* |
163122b7 | 6144 | * This is possible from callers such as attach_tasks(), in which we |
5238cdd3 PT |
6145 | * unconditionally check_prempt_curr() after an enqueue (which may have |
6146 | * lead to a throttle). This both saves work and prevents false | |
6147 | * next-buddy nomination below. | |
6148 | */ | |
6149 | if (unlikely(throttled_hierarchy(cfs_rq_of(pse)))) | |
6150 | return; | |
6151 | ||
2f36825b | 6152 | if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) { |
3cb63d52 | 6153 | set_next_buddy(pse); |
2f36825b VP |
6154 | next_buddy_marked = 1; |
6155 | } | |
57fdc26d | 6156 | |
aec0a514 BR |
6157 | /* |
6158 | * We can come here with TIF_NEED_RESCHED already set from new task | |
6159 | * wake up path. | |
5238cdd3 PT |
6160 | * |
6161 | * Note: this also catches the edge-case of curr being in a throttled | |
6162 | * group (e.g. via set_curr_task), since update_curr() (in the | |
6163 | * enqueue of curr) will have resulted in resched being set. This | |
6164 | * prevents us from potentially nominating it as a false LAST_BUDDY | |
6165 | * below. | |
aec0a514 BR |
6166 | */ |
6167 | if (test_tsk_need_resched(curr)) | |
6168 | return; | |
6169 | ||
a2f5c9ab DH |
6170 | /* Idle tasks are by definition preempted by non-idle tasks. */ |
6171 | if (unlikely(curr->policy == SCHED_IDLE) && | |
6172 | likely(p->policy != SCHED_IDLE)) | |
6173 | goto preempt; | |
6174 | ||
91c234b4 | 6175 | /* |
a2f5c9ab DH |
6176 | * Batch and idle tasks do not preempt non-idle tasks (their preemption |
6177 | * is driven by the tick): | |
91c234b4 | 6178 | */ |
8ed92e51 | 6179 | if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION)) |
91c234b4 | 6180 | return; |
bf0f6f24 | 6181 | |
464b7527 | 6182 | find_matching_se(&se, &pse); |
9bbd7374 | 6183 | update_curr(cfs_rq_of(se)); |
002f128b | 6184 | BUG_ON(!pse); |
2f36825b VP |
6185 | if (wakeup_preempt_entity(se, pse) == 1) { |
6186 | /* | |
6187 | * Bias pick_next to pick the sched entity that is | |
6188 | * triggering this preemption. | |
6189 | */ | |
6190 | if (!next_buddy_marked) | |
6191 | set_next_buddy(pse); | |
3a7e73a2 | 6192 | goto preempt; |
2f36825b | 6193 | } |
464b7527 | 6194 | |
3a7e73a2 | 6195 | return; |
a65ac745 | 6196 | |
3a7e73a2 | 6197 | preempt: |
8875125e | 6198 | resched_curr(rq); |
3a7e73a2 PZ |
6199 | /* |
6200 | * Only set the backward buddy when the current task is still | |
6201 | * on the rq. This can happen when a wakeup gets interleaved | |
6202 | * with schedule on the ->pre_schedule() or idle_balance() | |
6203 | * point, either of which can * drop the rq lock. | |
6204 | * | |
6205 | * Also, during early boot the idle thread is in the fair class, | |
6206 | * for obvious reasons its a bad idea to schedule back to it. | |
6207 | */ | |
6208 | if (unlikely(!se->on_rq || curr == rq->idle)) | |
6209 | return; | |
6210 | ||
6211 | if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se)) | |
6212 | set_last_buddy(se); | |
bf0f6f24 IM |
6213 | } |
6214 | ||
606dba2e | 6215 | static struct task_struct * |
d8ac8971 | 6216 | pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) |
bf0f6f24 IM |
6217 | { |
6218 | struct cfs_rq *cfs_rq = &rq->cfs; | |
6219 | struct sched_entity *se; | |
678d5718 | 6220 | struct task_struct *p; |
37e117c0 | 6221 | int new_tasks; |
678d5718 | 6222 | |
6e83125c | 6223 | again: |
678d5718 PZ |
6224 | #ifdef CONFIG_FAIR_GROUP_SCHED |
6225 | if (!cfs_rq->nr_running) | |
38033c37 | 6226 | goto idle; |
678d5718 | 6227 | |
3f1d2a31 | 6228 | if (prev->sched_class != &fair_sched_class) |
678d5718 PZ |
6229 | goto simple; |
6230 | ||
6231 | /* | |
6232 | * Because of the set_next_buddy() in dequeue_task_fair() it is rather | |
6233 | * likely that a next task is from the same cgroup as the current. | |
6234 | * | |
6235 | * Therefore attempt to avoid putting and setting the entire cgroup | |
6236 | * hierarchy, only change the part that actually changes. | |
6237 | */ | |
6238 | ||
6239 | do { | |
6240 | struct sched_entity *curr = cfs_rq->curr; | |
6241 | ||
6242 | /* | |
6243 | * Since we got here without doing put_prev_entity() we also | |
6244 | * have to consider cfs_rq->curr. If it is still a runnable | |
6245 | * entity, update_curr() will update its vruntime, otherwise | |
6246 | * forget we've ever seen it. | |
6247 | */ | |
54d27365 BS |
6248 | if (curr) { |
6249 | if (curr->on_rq) | |
6250 | update_curr(cfs_rq); | |
6251 | else | |
6252 | curr = NULL; | |
678d5718 | 6253 | |
54d27365 BS |
6254 | /* |
6255 | * This call to check_cfs_rq_runtime() will do the | |
6256 | * throttle and dequeue its entity in the parent(s). | |
6257 | * Therefore the 'simple' nr_running test will indeed | |
6258 | * be correct. | |
6259 | */ | |
6260 | if (unlikely(check_cfs_rq_runtime(cfs_rq))) | |
6261 | goto simple; | |
6262 | } | |
678d5718 PZ |
6263 | |
6264 | se = pick_next_entity(cfs_rq, curr); | |
6265 | cfs_rq = group_cfs_rq(se); | |
6266 | } while (cfs_rq); | |
6267 | ||
6268 | p = task_of(se); | |
6269 | ||
6270 | /* | |
6271 | * Since we haven't yet done put_prev_entity and if the selected task | |
6272 | * is a different task than we started out with, try and touch the | |
6273 | * least amount of cfs_rqs. | |
6274 | */ | |
6275 | if (prev != p) { | |
6276 | struct sched_entity *pse = &prev->se; | |
6277 | ||
6278 | while (!(cfs_rq = is_same_group(se, pse))) { | |
6279 | int se_depth = se->depth; | |
6280 | int pse_depth = pse->depth; | |
6281 | ||
6282 | if (se_depth <= pse_depth) { | |
6283 | put_prev_entity(cfs_rq_of(pse), pse); | |
6284 | pse = parent_entity(pse); | |
6285 | } | |
6286 | if (se_depth >= pse_depth) { | |
6287 | set_next_entity(cfs_rq_of(se), se); | |
6288 | se = parent_entity(se); | |
6289 | } | |
6290 | } | |
6291 | ||
6292 | put_prev_entity(cfs_rq, pse); | |
6293 | set_next_entity(cfs_rq, se); | |
6294 | } | |
6295 | ||
6296 | if (hrtick_enabled(rq)) | |
6297 | hrtick_start_fair(rq, p); | |
6298 | ||
6299 | return p; | |
6300 | simple: | |
6301 | cfs_rq = &rq->cfs; | |
6302 | #endif | |
bf0f6f24 | 6303 | |
36ace27e | 6304 | if (!cfs_rq->nr_running) |
38033c37 | 6305 | goto idle; |
bf0f6f24 | 6306 | |
3f1d2a31 | 6307 | put_prev_task(rq, prev); |
606dba2e | 6308 | |
bf0f6f24 | 6309 | do { |
678d5718 | 6310 | se = pick_next_entity(cfs_rq, NULL); |
f4b6755f | 6311 | set_next_entity(cfs_rq, se); |
bf0f6f24 IM |
6312 | cfs_rq = group_cfs_rq(se); |
6313 | } while (cfs_rq); | |
6314 | ||
8f4d37ec | 6315 | p = task_of(se); |
678d5718 | 6316 | |
b39e66ea MG |
6317 | if (hrtick_enabled(rq)) |
6318 | hrtick_start_fair(rq, p); | |
8f4d37ec PZ |
6319 | |
6320 | return p; | |
38033c37 PZ |
6321 | |
6322 | idle: | |
46f69fa3 MF |
6323 | new_tasks = idle_balance(rq, rf); |
6324 | ||
37e117c0 PZ |
6325 | /* |
6326 | * Because idle_balance() releases (and re-acquires) rq->lock, it is | |
6327 | * possible for any higher priority task to appear. In that case we | |
6328 | * must re-start the pick_next_entity() loop. | |
6329 | */ | |
e4aa358b | 6330 | if (new_tasks < 0) |
37e117c0 PZ |
6331 | return RETRY_TASK; |
6332 | ||
e4aa358b | 6333 | if (new_tasks > 0) |
38033c37 | 6334 | goto again; |
38033c37 PZ |
6335 | |
6336 | return NULL; | |
bf0f6f24 IM |
6337 | } |
6338 | ||
6339 | /* | |
6340 | * Account for a descheduled task: | |
6341 | */ | |
31ee529c | 6342 | static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) |
bf0f6f24 IM |
6343 | { |
6344 | struct sched_entity *se = &prev->se; | |
6345 | struct cfs_rq *cfs_rq; | |
6346 | ||
6347 | for_each_sched_entity(se) { | |
6348 | cfs_rq = cfs_rq_of(se); | |
ab6cde26 | 6349 | put_prev_entity(cfs_rq, se); |
bf0f6f24 IM |
6350 | } |
6351 | } | |
6352 | ||
ac53db59 RR |
6353 | /* |
6354 | * sched_yield() is very simple | |
6355 | * | |
6356 | * The magic of dealing with the ->skip buddy is in pick_next_entity. | |
6357 | */ | |
6358 | static void yield_task_fair(struct rq *rq) | |
6359 | { | |
6360 | struct task_struct *curr = rq->curr; | |
6361 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); | |
6362 | struct sched_entity *se = &curr->se; | |
6363 | ||
6364 | /* | |
6365 | * Are we the only task in the tree? | |
6366 | */ | |
6367 | if (unlikely(rq->nr_running == 1)) | |
6368 | return; | |
6369 | ||
6370 | clear_buddies(cfs_rq, se); | |
6371 | ||
6372 | if (curr->policy != SCHED_BATCH) { | |
6373 | update_rq_clock(rq); | |
6374 | /* | |
6375 | * Update run-time statistics of the 'current'. | |
6376 | */ | |
6377 | update_curr(cfs_rq); | |
916671c0 MG |
6378 | /* |
6379 | * Tell update_rq_clock() that we've just updated, | |
6380 | * so we don't do microscopic update in schedule() | |
6381 | * and double the fastpath cost. | |
6382 | */ | |
9edfbfed | 6383 | rq_clock_skip_update(rq, true); |
ac53db59 RR |
6384 | } |
6385 | ||
6386 | set_skip_buddy(se); | |
6387 | } | |
6388 | ||
d95f4122 MG |
6389 | static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) |
6390 | { | |
6391 | struct sched_entity *se = &p->se; | |
6392 | ||
5238cdd3 PT |
6393 | /* throttled hierarchies are not runnable */ |
6394 | if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se))) | |
d95f4122 MG |
6395 | return false; |
6396 | ||
6397 | /* Tell the scheduler that we'd really like pse to run next. */ | |
6398 | set_next_buddy(se); | |
6399 | ||
d95f4122 MG |
6400 | yield_task_fair(rq); |
6401 | ||
6402 | return true; | |
6403 | } | |
6404 | ||
681f3e68 | 6405 | #ifdef CONFIG_SMP |
bf0f6f24 | 6406 | /************************************************** |
e9c84cb8 PZ |
6407 | * Fair scheduling class load-balancing methods. |
6408 | * | |
6409 | * BASICS | |
6410 | * | |
6411 | * The purpose of load-balancing is to achieve the same basic fairness the | |
6412 | * per-cpu scheduler provides, namely provide a proportional amount of compute | |
6413 | * time to each task. This is expressed in the following equation: | |
6414 | * | |
6415 | * W_i,n/P_i == W_j,n/P_j for all i,j (1) | |
6416 | * | |
6417 | * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight | |
6418 | * W_i,0 is defined as: | |
6419 | * | |
6420 | * W_i,0 = \Sum_j w_i,j (2) | |
6421 | * | |
6422 | * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight | |
1c3de5e1 | 6423 | * is derived from the nice value as per sched_prio_to_weight[]. |
e9c84cb8 PZ |
6424 | * |
6425 | * The weight average is an exponential decay average of the instantaneous | |
6426 | * weight: | |
6427 | * | |
6428 | * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3) | |
6429 | * | |
ced549fa | 6430 | * C_i is the compute capacity of cpu i, typically it is the |
e9c84cb8 PZ |
6431 | * fraction of 'recent' time available for SCHED_OTHER task execution. But it |
6432 | * can also include other factors [XXX]. | |
6433 | * | |
6434 | * To achieve this balance we define a measure of imbalance which follows | |
6435 | * directly from (1): | |
6436 | * | |
ced549fa | 6437 | * imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j } (4) |
e9c84cb8 PZ |
6438 | * |
6439 | * We them move tasks around to minimize the imbalance. In the continuous | |
6440 | * function space it is obvious this converges, in the discrete case we get | |
6441 | * a few fun cases generally called infeasible weight scenarios. | |
6442 | * | |
6443 | * [XXX expand on: | |
6444 | * - infeasible weights; | |
6445 | * - local vs global optima in the discrete case. ] | |
6446 | * | |
6447 | * | |
6448 | * SCHED DOMAINS | |
6449 | * | |
6450 | * In order to solve the imbalance equation (4), and avoid the obvious O(n^2) | |
6451 | * for all i,j solution, we create a tree of cpus that follows the hardware | |
6452 | * topology where each level pairs two lower groups (or better). This results | |
6453 | * in O(log n) layers. Furthermore we reduce the number of cpus going up the | |
6454 | * tree to only the first of the previous level and we decrease the frequency | |
6455 | * of load-balance at each level inv. proportional to the number of cpus in | |
6456 | * the groups. | |
6457 | * | |
6458 | * This yields: | |
6459 | * | |
6460 | * log_2 n 1 n | |
6461 | * \Sum { --- * --- * 2^i } = O(n) (5) | |
6462 | * i = 0 2^i 2^i | |
6463 | * `- size of each group | |
6464 | * | | `- number of cpus doing load-balance | |
6465 | * | `- freq | |
6466 | * `- sum over all levels | |
6467 | * | |
6468 | * Coupled with a limit on how many tasks we can migrate every balance pass, | |
6469 | * this makes (5) the runtime complexity of the balancer. | |
6470 | * | |
6471 | * An important property here is that each CPU is still (indirectly) connected | |
6472 | * to every other cpu in at most O(log n) steps: | |
6473 | * | |
6474 | * The adjacency matrix of the resulting graph is given by: | |
6475 | * | |
97a7142f | 6476 | * log_2 n |
e9c84cb8 PZ |
6477 | * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6) |
6478 | * k = 0 | |
6479 | * | |
6480 | * And you'll find that: | |
6481 | * | |
6482 | * A^(log_2 n)_i,j != 0 for all i,j (7) | |
6483 | * | |
6484 | * Showing there's indeed a path between every cpu in at most O(log n) steps. | |
6485 | * The task movement gives a factor of O(m), giving a convergence complexity | |
6486 | * of: | |
6487 | * | |
6488 | * O(nm log n), n := nr_cpus, m := nr_tasks (8) | |
6489 | * | |
6490 | * | |
6491 | * WORK CONSERVING | |
6492 | * | |
6493 | * In order to avoid CPUs going idle while there's still work to do, new idle | |
6494 | * balancing is more aggressive and has the newly idle cpu iterate up the domain | |
6495 | * tree itself instead of relying on other CPUs to bring it work. | |
6496 | * | |
6497 | * This adds some complexity to both (5) and (8) but it reduces the total idle | |
6498 | * time. | |
6499 | * | |
6500 | * [XXX more?] | |
6501 | * | |
6502 | * | |
6503 | * CGROUPS | |
6504 | * | |
6505 | * Cgroups make a horror show out of (2), instead of a simple sum we get: | |
6506 | * | |
6507 | * s_k,i | |
6508 | * W_i,0 = \Sum_j \Prod_k w_k * ----- (9) | |
6509 | * S_k | |
6510 | * | |
6511 | * Where | |
6512 | * | |
6513 | * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10) | |
6514 | * | |
6515 | * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i. | |
6516 | * | |
6517 | * The big problem is S_k, its a global sum needed to compute a local (W_i) | |
6518 | * property. | |
6519 | * | |
6520 | * [XXX write more on how we solve this.. _after_ merging pjt's patches that | |
6521 | * rewrite all of this once again.] | |
97a7142f | 6522 | */ |
bf0f6f24 | 6523 | |
ed387b78 HS |
6524 | static unsigned long __read_mostly max_load_balance_interval = HZ/10; |
6525 | ||
0ec8aa00 PZ |
6526 | enum fbq_type { regular, remote, all }; |
6527 | ||
ddcdf6e7 | 6528 | #define LBF_ALL_PINNED 0x01 |
367456c7 | 6529 | #define LBF_NEED_BREAK 0x02 |
6263322c PZ |
6530 | #define LBF_DST_PINNED 0x04 |
6531 | #define LBF_SOME_PINNED 0x08 | |
ddcdf6e7 PZ |
6532 | |
6533 | struct lb_env { | |
6534 | struct sched_domain *sd; | |
6535 | ||
ddcdf6e7 | 6536 | struct rq *src_rq; |
85c1e7da | 6537 | int src_cpu; |
ddcdf6e7 PZ |
6538 | |
6539 | int dst_cpu; | |
6540 | struct rq *dst_rq; | |
6541 | ||
88b8dac0 SV |
6542 | struct cpumask *dst_grpmask; |
6543 | int new_dst_cpu; | |
ddcdf6e7 | 6544 | enum cpu_idle_type idle; |
bd939f45 | 6545 | long imbalance; |
b9403130 MW |
6546 | /* The set of CPUs under consideration for load-balancing */ |
6547 | struct cpumask *cpus; | |
6548 | ||
ddcdf6e7 | 6549 | unsigned int flags; |
367456c7 PZ |
6550 | |
6551 | unsigned int loop; | |
6552 | unsigned int loop_break; | |
6553 | unsigned int loop_max; | |
0ec8aa00 PZ |
6554 | |
6555 | enum fbq_type fbq_type; | |
163122b7 | 6556 | struct list_head tasks; |
ddcdf6e7 PZ |
6557 | }; |
6558 | ||
029632fb PZ |
6559 | /* |
6560 | * Is this task likely cache-hot: | |
6561 | */ | |
5d5e2b1b | 6562 | static int task_hot(struct task_struct *p, struct lb_env *env) |
029632fb PZ |
6563 | { |
6564 | s64 delta; | |
6565 | ||
e5673f28 KT |
6566 | lockdep_assert_held(&env->src_rq->lock); |
6567 | ||
029632fb PZ |
6568 | if (p->sched_class != &fair_sched_class) |
6569 | return 0; | |
6570 | ||
6571 | if (unlikely(p->policy == SCHED_IDLE)) | |
6572 | return 0; | |
6573 | ||
6574 | /* | |
6575 | * Buddy candidates are cache hot: | |
6576 | */ | |
5d5e2b1b | 6577 | if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running && |
029632fb PZ |
6578 | (&p->se == cfs_rq_of(&p->se)->next || |
6579 | &p->se == cfs_rq_of(&p->se)->last)) | |
6580 | return 1; | |
6581 | ||
6582 | if (sysctl_sched_migration_cost == -1) | |
6583 | return 1; | |
6584 | if (sysctl_sched_migration_cost == 0) | |
6585 | return 0; | |
6586 | ||
5d5e2b1b | 6587 | delta = rq_clock_task(env->src_rq) - p->se.exec_start; |
029632fb PZ |
6588 | |
6589 | return delta < (s64)sysctl_sched_migration_cost; | |
6590 | } | |
6591 | ||
3a7053b3 | 6592 | #ifdef CONFIG_NUMA_BALANCING |
c1ceac62 | 6593 | /* |
2a1ed24c SD |
6594 | * Returns 1, if task migration degrades locality |
6595 | * Returns 0, if task migration improves locality i.e migration preferred. | |
6596 | * Returns -1, if task migration is not affected by locality. | |
c1ceac62 | 6597 | */ |
2a1ed24c | 6598 | static int migrate_degrades_locality(struct task_struct *p, struct lb_env *env) |
3a7053b3 | 6599 | { |
b1ad065e | 6600 | struct numa_group *numa_group = rcu_dereference(p->numa_group); |
c1ceac62 | 6601 | unsigned long src_faults, dst_faults; |
3a7053b3 MG |
6602 | int src_nid, dst_nid; |
6603 | ||
2a595721 | 6604 | if (!static_branch_likely(&sched_numa_balancing)) |
2a1ed24c SD |
6605 | return -1; |
6606 | ||
c3b9bc5b | 6607 | if (!p->numa_faults || !(env->sd->flags & SD_NUMA)) |
2a1ed24c | 6608 | return -1; |
7a0f3083 MG |
6609 | |
6610 | src_nid = cpu_to_node(env->src_cpu); | |
6611 | dst_nid = cpu_to_node(env->dst_cpu); | |
6612 | ||
83e1d2cd | 6613 | if (src_nid == dst_nid) |
2a1ed24c | 6614 | return -1; |
7a0f3083 | 6615 | |
2a1ed24c SD |
6616 | /* Migrating away from the preferred node is always bad. */ |
6617 | if (src_nid == p->numa_preferred_nid) { | |
6618 | if (env->src_rq->nr_running > env->src_rq->nr_preferred_running) | |
6619 | return 1; | |
6620 | else | |
6621 | return -1; | |
6622 | } | |
b1ad065e | 6623 | |
c1ceac62 RR |
6624 | /* Encourage migration to the preferred node. */ |
6625 | if (dst_nid == p->numa_preferred_nid) | |
2a1ed24c | 6626 | return 0; |
b1ad065e | 6627 | |
c1ceac62 RR |
6628 | if (numa_group) { |
6629 | src_faults = group_faults(p, src_nid); | |
6630 | dst_faults = group_faults(p, dst_nid); | |
6631 | } else { | |
6632 | src_faults = task_faults(p, src_nid); | |
6633 | dst_faults = task_faults(p, dst_nid); | |
b1ad065e RR |
6634 | } |
6635 | ||
c1ceac62 | 6636 | return dst_faults < src_faults; |
7a0f3083 MG |
6637 | } |
6638 | ||
3a7053b3 | 6639 | #else |
2a1ed24c | 6640 | static inline int migrate_degrades_locality(struct task_struct *p, |
3a7053b3 MG |
6641 | struct lb_env *env) |
6642 | { | |
2a1ed24c | 6643 | return -1; |
7a0f3083 | 6644 | } |
3a7053b3 MG |
6645 | #endif |
6646 | ||
1e3c88bd PZ |
6647 | /* |
6648 | * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? | |
6649 | */ | |
6650 | static | |
8e45cb54 | 6651 | int can_migrate_task(struct task_struct *p, struct lb_env *env) |
1e3c88bd | 6652 | { |
2a1ed24c | 6653 | int tsk_cache_hot; |
e5673f28 KT |
6654 | |
6655 | lockdep_assert_held(&env->src_rq->lock); | |
6656 | ||
1e3c88bd PZ |
6657 | /* |
6658 | * We do not migrate tasks that are: | |
d3198084 | 6659 | * 1) throttled_lb_pair, or |
1e3c88bd | 6660 | * 2) cannot be migrated to this CPU due to cpus_allowed, or |
d3198084 JK |
6661 | * 3) running (obviously), or |
6662 | * 4) are cache-hot on their current CPU. | |
1e3c88bd | 6663 | */ |
d3198084 JK |
6664 | if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) |
6665 | return 0; | |
6666 | ||
ddcdf6e7 | 6667 | if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) { |
e02e60c1 | 6668 | int cpu; |
88b8dac0 | 6669 | |
ae92882e | 6670 | schedstat_inc(p->se.statistics.nr_failed_migrations_affine); |
88b8dac0 | 6671 | |
6263322c PZ |
6672 | env->flags |= LBF_SOME_PINNED; |
6673 | ||
88b8dac0 SV |
6674 | /* |
6675 | * Remember if this task can be migrated to any other cpu in | |
6676 | * our sched_group. We may want to revisit it if we couldn't | |
6677 | * meet load balance goals by pulling other tasks on src_cpu. | |
6678 | * | |
6679 | * Also avoid computing new_dst_cpu if we have already computed | |
6680 | * one in current iteration. | |
6681 | */ | |
6263322c | 6682 | if (!env->dst_grpmask || (env->flags & LBF_DST_PINNED)) |
88b8dac0 SV |
6683 | return 0; |
6684 | ||
e02e60c1 JK |
6685 | /* Prevent to re-select dst_cpu via env's cpus */ |
6686 | for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) { | |
6687 | if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) { | |
6263322c | 6688 | env->flags |= LBF_DST_PINNED; |
e02e60c1 JK |
6689 | env->new_dst_cpu = cpu; |
6690 | break; | |
6691 | } | |
88b8dac0 | 6692 | } |
e02e60c1 | 6693 | |
1e3c88bd PZ |
6694 | return 0; |
6695 | } | |
88b8dac0 SV |
6696 | |
6697 | /* Record that we found atleast one task that could run on dst_cpu */ | |
8e45cb54 | 6698 | env->flags &= ~LBF_ALL_PINNED; |
1e3c88bd | 6699 | |
ddcdf6e7 | 6700 | if (task_running(env->src_rq, p)) { |
ae92882e | 6701 | schedstat_inc(p->se.statistics.nr_failed_migrations_running); |
1e3c88bd PZ |
6702 | return 0; |
6703 | } | |
6704 | ||
6705 | /* | |
6706 | * Aggressive migration if: | |
3a7053b3 MG |
6707 | * 1) destination numa is preferred |
6708 | * 2) task is cache cold, or | |
6709 | * 3) too many balance attempts have failed. | |
1e3c88bd | 6710 | */ |
2a1ed24c SD |
6711 | tsk_cache_hot = migrate_degrades_locality(p, env); |
6712 | if (tsk_cache_hot == -1) | |
6713 | tsk_cache_hot = task_hot(p, env); | |
3a7053b3 | 6714 | |
2a1ed24c | 6715 | if (tsk_cache_hot <= 0 || |
7a96c231 | 6716 | env->sd->nr_balance_failed > env->sd->cache_nice_tries) { |
2a1ed24c | 6717 | if (tsk_cache_hot == 1) { |
ae92882e JP |
6718 | schedstat_inc(env->sd->lb_hot_gained[env->idle]); |
6719 | schedstat_inc(p->se.statistics.nr_forced_migrations); | |
3a7053b3 | 6720 | } |
1e3c88bd PZ |
6721 | return 1; |
6722 | } | |
6723 | ||
ae92882e | 6724 | schedstat_inc(p->se.statistics.nr_failed_migrations_hot); |
4e2dcb73 | 6725 | return 0; |
1e3c88bd PZ |
6726 | } |
6727 | ||
897c395f | 6728 | /* |
163122b7 KT |
6729 | * detach_task() -- detach the task for the migration specified in env |
6730 | */ | |
6731 | static void detach_task(struct task_struct *p, struct lb_env *env) | |
6732 | { | |
6733 | lockdep_assert_held(&env->src_rq->lock); | |
6734 | ||
163122b7 | 6735 | p->on_rq = TASK_ON_RQ_MIGRATING; |
3ea94de1 | 6736 | deactivate_task(env->src_rq, p, 0); |
163122b7 KT |
6737 | set_task_cpu(p, env->dst_cpu); |
6738 | } | |
6739 | ||
897c395f | 6740 | /* |
e5673f28 | 6741 | * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as |
897c395f | 6742 | * part of active balancing operations within "domain". |
897c395f | 6743 | * |
e5673f28 | 6744 | * Returns a task if successful and NULL otherwise. |
897c395f | 6745 | */ |
e5673f28 | 6746 | static struct task_struct *detach_one_task(struct lb_env *env) |
897c395f PZ |
6747 | { |
6748 | struct task_struct *p, *n; | |
897c395f | 6749 | |
e5673f28 KT |
6750 | lockdep_assert_held(&env->src_rq->lock); |
6751 | ||
367456c7 | 6752 | list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) { |
367456c7 PZ |
6753 | if (!can_migrate_task(p, env)) |
6754 | continue; | |
897c395f | 6755 | |
163122b7 | 6756 | detach_task(p, env); |
e5673f28 | 6757 | |
367456c7 | 6758 | /* |
e5673f28 | 6759 | * Right now, this is only the second place where |
163122b7 | 6760 | * lb_gained[env->idle] is updated (other is detach_tasks) |
e5673f28 | 6761 | * so we can safely collect stats here rather than |
163122b7 | 6762 | * inside detach_tasks(). |
367456c7 | 6763 | */ |
ae92882e | 6764 | schedstat_inc(env->sd->lb_gained[env->idle]); |
e5673f28 | 6765 | return p; |
897c395f | 6766 | } |
e5673f28 | 6767 | return NULL; |
897c395f PZ |
6768 | } |
6769 | ||
eb95308e PZ |
6770 | static const unsigned int sched_nr_migrate_break = 32; |
6771 | ||
5d6523eb | 6772 | /* |
163122b7 KT |
6773 | * detach_tasks() -- tries to detach up to imbalance weighted load from |
6774 | * busiest_rq, as part of a balancing operation within domain "sd". | |
5d6523eb | 6775 | * |
163122b7 | 6776 | * Returns number of detached tasks if successful and 0 otherwise. |
5d6523eb | 6777 | */ |
163122b7 | 6778 | static int detach_tasks(struct lb_env *env) |
1e3c88bd | 6779 | { |
5d6523eb PZ |
6780 | struct list_head *tasks = &env->src_rq->cfs_tasks; |
6781 | struct task_struct *p; | |
367456c7 | 6782 | unsigned long load; |
163122b7 KT |
6783 | int detached = 0; |
6784 | ||
6785 | lockdep_assert_held(&env->src_rq->lock); | |
1e3c88bd | 6786 | |
bd939f45 | 6787 | if (env->imbalance <= 0) |
5d6523eb | 6788 | return 0; |
1e3c88bd | 6789 | |
5d6523eb | 6790 | while (!list_empty(tasks)) { |
985d3a4c YD |
6791 | /* |
6792 | * We don't want to steal all, otherwise we may be treated likewise, | |
6793 | * which could at worst lead to a livelock crash. | |
6794 | */ | |
6795 | if (env->idle != CPU_NOT_IDLE && env->src_rq->nr_running <= 1) | |
6796 | break; | |
6797 | ||
5d6523eb | 6798 | p = list_first_entry(tasks, struct task_struct, se.group_node); |
1e3c88bd | 6799 | |
367456c7 PZ |
6800 | env->loop++; |
6801 | /* We've more or less seen every task there is, call it quits */ | |
5d6523eb | 6802 | if (env->loop > env->loop_max) |
367456c7 | 6803 | break; |
5d6523eb PZ |
6804 | |
6805 | /* take a breather every nr_migrate tasks */ | |
367456c7 | 6806 | if (env->loop > env->loop_break) { |
eb95308e | 6807 | env->loop_break += sched_nr_migrate_break; |
8e45cb54 | 6808 | env->flags |= LBF_NEED_BREAK; |
ee00e66f | 6809 | break; |
a195f004 | 6810 | } |
1e3c88bd | 6811 | |
d3198084 | 6812 | if (!can_migrate_task(p, env)) |
367456c7 PZ |
6813 | goto next; |
6814 | ||
6815 | load = task_h_load(p); | |
5d6523eb | 6816 | |
eb95308e | 6817 | if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed) |
367456c7 PZ |
6818 | goto next; |
6819 | ||
bd939f45 | 6820 | if ((load / 2) > env->imbalance) |
367456c7 | 6821 | goto next; |
1e3c88bd | 6822 | |
163122b7 KT |
6823 | detach_task(p, env); |
6824 | list_add(&p->se.group_node, &env->tasks); | |
6825 | ||
6826 | detached++; | |
bd939f45 | 6827 | env->imbalance -= load; |
1e3c88bd PZ |
6828 | |
6829 | #ifdef CONFIG_PREEMPT | |
ee00e66f PZ |
6830 | /* |
6831 | * NEWIDLE balancing is a source of latency, so preemptible | |
163122b7 | 6832 | * kernels will stop after the first task is detached to minimize |
ee00e66f PZ |
6833 | * the critical section. |
6834 | */ | |
5d6523eb | 6835 | if (env->idle == CPU_NEWLY_IDLE) |
ee00e66f | 6836 | break; |
1e3c88bd PZ |
6837 | #endif |
6838 | ||
ee00e66f PZ |
6839 | /* |
6840 | * We only want to steal up to the prescribed amount of | |
6841 | * weighted load. | |
6842 | */ | |
bd939f45 | 6843 | if (env->imbalance <= 0) |
ee00e66f | 6844 | break; |
367456c7 PZ |
6845 | |
6846 | continue; | |
6847 | next: | |
5d6523eb | 6848 | list_move_tail(&p->se.group_node, tasks); |
1e3c88bd | 6849 | } |
5d6523eb | 6850 | |
1e3c88bd | 6851 | /* |
163122b7 KT |
6852 | * Right now, this is one of only two places we collect this stat |
6853 | * so we can safely collect detach_one_task() stats here rather | |
6854 | * than inside detach_one_task(). | |
1e3c88bd | 6855 | */ |
ae92882e | 6856 | schedstat_add(env->sd->lb_gained[env->idle], detached); |
1e3c88bd | 6857 | |
163122b7 KT |
6858 | return detached; |
6859 | } | |
6860 | ||
6861 | /* | |
6862 | * attach_task() -- attach the task detached by detach_task() to its new rq. | |
6863 | */ | |
6864 | static void attach_task(struct rq *rq, struct task_struct *p) | |
6865 | { | |
6866 | lockdep_assert_held(&rq->lock); | |
6867 | ||
6868 | BUG_ON(task_rq(p) != rq); | |
163122b7 | 6869 | activate_task(rq, p, 0); |
3ea94de1 | 6870 | p->on_rq = TASK_ON_RQ_QUEUED; |
163122b7 KT |
6871 | check_preempt_curr(rq, p, 0); |
6872 | } | |
6873 | ||
6874 | /* | |
6875 | * attach_one_task() -- attaches the task returned from detach_one_task() to | |
6876 | * its new rq. | |
6877 | */ | |
6878 | static void attach_one_task(struct rq *rq, struct task_struct *p) | |
6879 | { | |
6880 | raw_spin_lock(&rq->lock); | |
6881 | attach_task(rq, p); | |
6882 | raw_spin_unlock(&rq->lock); | |
6883 | } | |
6884 | ||
6885 | /* | |
6886 | * attach_tasks() -- attaches all tasks detached by detach_tasks() to their | |
6887 | * new rq. | |
6888 | */ | |
6889 | static void attach_tasks(struct lb_env *env) | |
6890 | { | |
6891 | struct list_head *tasks = &env->tasks; | |
6892 | struct task_struct *p; | |
6893 | ||
6894 | raw_spin_lock(&env->dst_rq->lock); | |
6895 | ||
6896 | while (!list_empty(tasks)) { | |
6897 | p = list_first_entry(tasks, struct task_struct, se.group_node); | |
6898 | list_del_init(&p->se.group_node); | |
1e3c88bd | 6899 | |
163122b7 KT |
6900 | attach_task(env->dst_rq, p); |
6901 | } | |
6902 | ||
6903 | raw_spin_unlock(&env->dst_rq->lock); | |
1e3c88bd PZ |
6904 | } |
6905 | ||
230059de | 6906 | #ifdef CONFIG_FAIR_GROUP_SCHED |
48a16753 | 6907 | static void update_blocked_averages(int cpu) |
9e3081ca | 6908 | { |
9e3081ca | 6909 | struct rq *rq = cpu_rq(cpu); |
48a16753 PT |
6910 | struct cfs_rq *cfs_rq; |
6911 | unsigned long flags; | |
9e3081ca | 6912 | |
48a16753 PT |
6913 | raw_spin_lock_irqsave(&rq->lock, flags); |
6914 | update_rq_clock(rq); | |
9d89c257 | 6915 | |
9763b67f PZ |
6916 | /* |
6917 | * Iterates the task_group tree in a bottom up fashion, see | |
6918 | * list_add_leaf_cfs_rq() for details. | |
6919 | */ | |
64660c86 | 6920 | for_each_leaf_cfs_rq(rq, cfs_rq) { |
9d89c257 YD |
6921 | /* throttled entities do not contribute to load */ |
6922 | if (throttled_hierarchy(cfs_rq)) | |
6923 | continue; | |
48a16753 | 6924 | |
a2c6c91f | 6925 | if (update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq, true)) |
9d89c257 | 6926 | update_tg_load_avg(cfs_rq, 0); |
4e516076 VG |
6927 | |
6928 | /* Propagate pending load changes to the parent */ | |
6929 | if (cfs_rq->tg->se[cpu]) | |
6930 | update_load_avg(cfs_rq->tg->se[cpu], 0); | |
9d89c257 | 6931 | } |
48a16753 | 6932 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
9e3081ca PZ |
6933 | } |
6934 | ||
9763b67f | 6935 | /* |
68520796 | 6936 | * Compute the hierarchical load factor for cfs_rq and all its ascendants. |
9763b67f PZ |
6937 | * This needs to be done in a top-down fashion because the load of a child |
6938 | * group is a fraction of its parents load. | |
6939 | */ | |
68520796 | 6940 | static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq) |
9763b67f | 6941 | { |
68520796 VD |
6942 | struct rq *rq = rq_of(cfs_rq); |
6943 | struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)]; | |
a35b6466 | 6944 | unsigned long now = jiffies; |
68520796 | 6945 | unsigned long load; |
a35b6466 | 6946 | |
68520796 | 6947 | if (cfs_rq->last_h_load_update == now) |
a35b6466 PZ |
6948 | return; |
6949 | ||
68520796 VD |
6950 | cfs_rq->h_load_next = NULL; |
6951 | for_each_sched_entity(se) { | |
6952 | cfs_rq = cfs_rq_of(se); | |
6953 | cfs_rq->h_load_next = se; | |
6954 | if (cfs_rq->last_h_load_update == now) | |
6955 | break; | |
6956 | } | |
a35b6466 | 6957 | |
68520796 | 6958 | if (!se) { |
7ea241af | 6959 | cfs_rq->h_load = cfs_rq_load_avg(cfs_rq); |
68520796 VD |
6960 | cfs_rq->last_h_load_update = now; |
6961 | } | |
6962 | ||
6963 | while ((se = cfs_rq->h_load_next) != NULL) { | |
6964 | load = cfs_rq->h_load; | |
7ea241af YD |
6965 | load = div64_ul(load * se->avg.load_avg, |
6966 | cfs_rq_load_avg(cfs_rq) + 1); | |
68520796 VD |
6967 | cfs_rq = group_cfs_rq(se); |
6968 | cfs_rq->h_load = load; | |
6969 | cfs_rq->last_h_load_update = now; | |
6970 | } | |
9763b67f PZ |
6971 | } |
6972 | ||
367456c7 | 6973 | static unsigned long task_h_load(struct task_struct *p) |
230059de | 6974 | { |
367456c7 | 6975 | struct cfs_rq *cfs_rq = task_cfs_rq(p); |
230059de | 6976 | |
68520796 | 6977 | update_cfs_rq_h_load(cfs_rq); |
9d89c257 | 6978 | return div64_ul(p->se.avg.load_avg * cfs_rq->h_load, |
7ea241af | 6979 | cfs_rq_load_avg(cfs_rq) + 1); |
230059de PZ |
6980 | } |
6981 | #else | |
48a16753 | 6982 | static inline void update_blocked_averages(int cpu) |
9e3081ca | 6983 | { |
6c1d47c0 VG |
6984 | struct rq *rq = cpu_rq(cpu); |
6985 | struct cfs_rq *cfs_rq = &rq->cfs; | |
6986 | unsigned long flags; | |
6987 | ||
6988 | raw_spin_lock_irqsave(&rq->lock, flags); | |
6989 | update_rq_clock(rq); | |
a2c6c91f | 6990 | update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq, true); |
6c1d47c0 | 6991 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
9e3081ca PZ |
6992 | } |
6993 | ||
367456c7 | 6994 | static unsigned long task_h_load(struct task_struct *p) |
1e3c88bd | 6995 | { |
9d89c257 | 6996 | return p->se.avg.load_avg; |
1e3c88bd | 6997 | } |
230059de | 6998 | #endif |
1e3c88bd | 6999 | |
1e3c88bd | 7000 | /********** Helpers for find_busiest_group ************************/ |
caeb178c RR |
7001 | |
7002 | enum group_type { | |
7003 | group_other = 0, | |
7004 | group_imbalanced, | |
7005 | group_overloaded, | |
7006 | }; | |
7007 | ||
1e3c88bd PZ |
7008 | /* |
7009 | * sg_lb_stats - stats of a sched_group required for load_balancing | |
7010 | */ | |
7011 | struct sg_lb_stats { | |
7012 | unsigned long avg_load; /*Avg load across the CPUs of the group */ | |
7013 | unsigned long group_load; /* Total load over the CPUs of the group */ | |
1e3c88bd | 7014 | unsigned long sum_weighted_load; /* Weighted load of group's tasks */ |
56cf515b | 7015 | unsigned long load_per_task; |
63b2ca30 | 7016 | unsigned long group_capacity; |
9e91d61d | 7017 | unsigned long group_util; /* Total utilization of the group */ |
147c5fc2 | 7018 | unsigned int sum_nr_running; /* Nr tasks running in the group */ |
147c5fc2 PZ |
7019 | unsigned int idle_cpus; |
7020 | unsigned int group_weight; | |
caeb178c | 7021 | enum group_type group_type; |
ea67821b | 7022 | int group_no_capacity; |
0ec8aa00 PZ |
7023 | #ifdef CONFIG_NUMA_BALANCING |
7024 | unsigned int nr_numa_running; | |
7025 | unsigned int nr_preferred_running; | |
7026 | #endif | |
1e3c88bd PZ |
7027 | }; |
7028 | ||
56cf515b JK |
7029 | /* |
7030 | * sd_lb_stats - Structure to store the statistics of a sched_domain | |
7031 | * during load balancing. | |
7032 | */ | |
7033 | struct sd_lb_stats { | |
7034 | struct sched_group *busiest; /* Busiest group in this sd */ | |
7035 | struct sched_group *local; /* Local group in this sd */ | |
7036 | unsigned long total_load; /* Total load of all groups in sd */ | |
63b2ca30 | 7037 | unsigned long total_capacity; /* Total capacity of all groups in sd */ |
56cf515b JK |
7038 | unsigned long avg_load; /* Average load across all groups in sd */ |
7039 | ||
56cf515b | 7040 | struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */ |
147c5fc2 | 7041 | struct sg_lb_stats local_stat; /* Statistics of the local group */ |
56cf515b JK |
7042 | }; |
7043 | ||
147c5fc2 PZ |
7044 | static inline void init_sd_lb_stats(struct sd_lb_stats *sds) |
7045 | { | |
7046 | /* | |
7047 | * Skimp on the clearing to avoid duplicate work. We can avoid clearing | |
7048 | * local_stat because update_sg_lb_stats() does a full clear/assignment. | |
7049 | * We must however clear busiest_stat::avg_load because | |
7050 | * update_sd_pick_busiest() reads this before assignment. | |
7051 | */ | |
7052 | *sds = (struct sd_lb_stats){ | |
7053 | .busiest = NULL, | |
7054 | .local = NULL, | |
7055 | .total_load = 0UL, | |
63b2ca30 | 7056 | .total_capacity = 0UL, |
147c5fc2 PZ |
7057 | .busiest_stat = { |
7058 | .avg_load = 0UL, | |
caeb178c RR |
7059 | .sum_nr_running = 0, |
7060 | .group_type = group_other, | |
147c5fc2 PZ |
7061 | }, |
7062 | }; | |
7063 | } | |
7064 | ||
1e3c88bd PZ |
7065 | /** |
7066 | * get_sd_load_idx - Obtain the load index for a given sched domain. | |
7067 | * @sd: The sched_domain whose load_idx is to be obtained. | |
ed1b7732 | 7068 | * @idle: The idle status of the CPU for whose sd load_idx is obtained. |
e69f6186 YB |
7069 | * |
7070 | * Return: The load index. | |
1e3c88bd PZ |
7071 | */ |
7072 | static inline int get_sd_load_idx(struct sched_domain *sd, | |
7073 | enum cpu_idle_type idle) | |
7074 | { | |
7075 | int load_idx; | |
7076 | ||
7077 | switch (idle) { | |
7078 | case CPU_NOT_IDLE: | |
7079 | load_idx = sd->busy_idx; | |
7080 | break; | |
7081 | ||
7082 | case CPU_NEWLY_IDLE: | |
7083 | load_idx = sd->newidle_idx; | |
7084 | break; | |
7085 | default: | |
7086 | load_idx = sd->idle_idx; | |
7087 | break; | |
7088 | } | |
7089 | ||
7090 | return load_idx; | |
7091 | } | |
7092 | ||
ced549fa | 7093 | static unsigned long scale_rt_capacity(int cpu) |
1e3c88bd PZ |
7094 | { |
7095 | struct rq *rq = cpu_rq(cpu); | |
b5b4860d | 7096 | u64 total, used, age_stamp, avg; |
cadefd3d | 7097 | s64 delta; |
1e3c88bd | 7098 | |
b654f7de PZ |
7099 | /* |
7100 | * Since we're reading these variables without serialization make sure | |
7101 | * we read them once before doing sanity checks on them. | |
7102 | */ | |
316c1608 JL |
7103 | age_stamp = READ_ONCE(rq->age_stamp); |
7104 | avg = READ_ONCE(rq->rt_avg); | |
cebde6d6 | 7105 | delta = __rq_clock_broken(rq) - age_stamp; |
b654f7de | 7106 | |
cadefd3d PZ |
7107 | if (unlikely(delta < 0)) |
7108 | delta = 0; | |
7109 | ||
7110 | total = sched_avg_period() + delta; | |
aa483808 | 7111 | |
b5b4860d | 7112 | used = div_u64(avg, total); |
1e3c88bd | 7113 | |
b5b4860d VG |
7114 | if (likely(used < SCHED_CAPACITY_SCALE)) |
7115 | return SCHED_CAPACITY_SCALE - used; | |
1e3c88bd | 7116 | |
b5b4860d | 7117 | return 1; |
1e3c88bd PZ |
7118 | } |
7119 | ||
ced549fa | 7120 | static void update_cpu_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 7121 | { |
8cd5601c | 7122 | unsigned long capacity = arch_scale_cpu_capacity(sd, cpu); |
1e3c88bd PZ |
7123 | struct sched_group *sdg = sd->groups; |
7124 | ||
ca6d75e6 | 7125 | cpu_rq(cpu)->cpu_capacity_orig = capacity; |
9d5efe05 | 7126 | |
ced549fa | 7127 | capacity *= scale_rt_capacity(cpu); |
ca8ce3d0 | 7128 | capacity >>= SCHED_CAPACITY_SHIFT; |
1e3c88bd | 7129 | |
ced549fa NP |
7130 | if (!capacity) |
7131 | capacity = 1; | |
1e3c88bd | 7132 | |
ced549fa NP |
7133 | cpu_rq(cpu)->cpu_capacity = capacity; |
7134 | sdg->sgc->capacity = capacity; | |
bf475ce0 | 7135 | sdg->sgc->min_capacity = capacity; |
1e3c88bd PZ |
7136 | } |
7137 | ||
63b2ca30 | 7138 | void update_group_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd PZ |
7139 | { |
7140 | struct sched_domain *child = sd->child; | |
7141 | struct sched_group *group, *sdg = sd->groups; | |
bf475ce0 | 7142 | unsigned long capacity, min_capacity; |
4ec4412e VG |
7143 | unsigned long interval; |
7144 | ||
7145 | interval = msecs_to_jiffies(sd->balance_interval); | |
7146 | interval = clamp(interval, 1UL, max_load_balance_interval); | |
63b2ca30 | 7147 | sdg->sgc->next_update = jiffies + interval; |
1e3c88bd PZ |
7148 | |
7149 | if (!child) { | |
ced549fa | 7150 | update_cpu_capacity(sd, cpu); |
1e3c88bd PZ |
7151 | return; |
7152 | } | |
7153 | ||
dc7ff76e | 7154 | capacity = 0; |
bf475ce0 | 7155 | min_capacity = ULONG_MAX; |
1e3c88bd | 7156 | |
74a5ce20 PZ |
7157 | if (child->flags & SD_OVERLAP) { |
7158 | /* | |
7159 | * SD_OVERLAP domains cannot assume that child groups | |
7160 | * span the current group. | |
7161 | */ | |
7162 | ||
863bffc8 | 7163 | for_each_cpu(cpu, sched_group_cpus(sdg)) { |
63b2ca30 | 7164 | struct sched_group_capacity *sgc; |
9abf24d4 | 7165 | struct rq *rq = cpu_rq(cpu); |
863bffc8 | 7166 | |
9abf24d4 | 7167 | /* |
63b2ca30 | 7168 | * build_sched_domains() -> init_sched_groups_capacity() |
9abf24d4 SD |
7169 | * gets here before we've attached the domains to the |
7170 | * runqueues. | |
7171 | * | |
ced549fa NP |
7172 | * Use capacity_of(), which is set irrespective of domains |
7173 | * in update_cpu_capacity(). | |
9abf24d4 | 7174 | * |
dc7ff76e | 7175 | * This avoids capacity from being 0 and |
9abf24d4 | 7176 | * causing divide-by-zero issues on boot. |
9abf24d4 SD |
7177 | */ |
7178 | if (unlikely(!rq->sd)) { | |
ced549fa | 7179 | capacity += capacity_of(cpu); |
bf475ce0 MR |
7180 | } else { |
7181 | sgc = rq->sd->groups->sgc; | |
7182 | capacity += sgc->capacity; | |
9abf24d4 | 7183 | } |
863bffc8 | 7184 | |
bf475ce0 | 7185 | min_capacity = min(capacity, min_capacity); |
863bffc8 | 7186 | } |
74a5ce20 PZ |
7187 | } else { |
7188 | /* | |
7189 | * !SD_OVERLAP domains can assume that child groups | |
7190 | * span the current group. | |
97a7142f | 7191 | */ |
74a5ce20 PZ |
7192 | |
7193 | group = child->groups; | |
7194 | do { | |
bf475ce0 MR |
7195 | struct sched_group_capacity *sgc = group->sgc; |
7196 | ||
7197 | capacity += sgc->capacity; | |
7198 | min_capacity = min(sgc->min_capacity, min_capacity); | |
74a5ce20 PZ |
7199 | group = group->next; |
7200 | } while (group != child->groups); | |
7201 | } | |
1e3c88bd | 7202 | |
63b2ca30 | 7203 | sdg->sgc->capacity = capacity; |
bf475ce0 | 7204 | sdg->sgc->min_capacity = min_capacity; |
1e3c88bd PZ |
7205 | } |
7206 | ||
9d5efe05 | 7207 | /* |
ea67821b VG |
7208 | * Check whether the capacity of the rq has been noticeably reduced by side |
7209 | * activity. The imbalance_pct is used for the threshold. | |
7210 | * Return true is the capacity is reduced | |
9d5efe05 SV |
7211 | */ |
7212 | static inline int | |
ea67821b | 7213 | check_cpu_capacity(struct rq *rq, struct sched_domain *sd) |
9d5efe05 | 7214 | { |
ea67821b VG |
7215 | return ((rq->cpu_capacity * sd->imbalance_pct) < |
7216 | (rq->cpu_capacity_orig * 100)); | |
9d5efe05 SV |
7217 | } |
7218 | ||
30ce5dab PZ |
7219 | /* |
7220 | * Group imbalance indicates (and tries to solve) the problem where balancing | |
7221 | * groups is inadequate due to tsk_cpus_allowed() constraints. | |
7222 | * | |
7223 | * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a | |
7224 | * cpumask covering 1 cpu of the first group and 3 cpus of the second group. | |
7225 | * Something like: | |
7226 | * | |
2b4d5b25 IM |
7227 | * { 0 1 2 3 } { 4 5 6 7 } |
7228 | * * * * * | |
30ce5dab PZ |
7229 | * |
7230 | * If we were to balance group-wise we'd place two tasks in the first group and | |
7231 | * two tasks in the second group. Clearly this is undesired as it will overload | |
7232 | * cpu 3 and leave one of the cpus in the second group unused. | |
7233 | * | |
7234 | * The current solution to this issue is detecting the skew in the first group | |
6263322c PZ |
7235 | * by noticing the lower domain failed to reach balance and had difficulty |
7236 | * moving tasks due to affinity constraints. | |
30ce5dab PZ |
7237 | * |
7238 | * When this is so detected; this group becomes a candidate for busiest; see | |
ed1b7732 | 7239 | * update_sd_pick_busiest(). And calculate_imbalance() and |
6263322c | 7240 | * find_busiest_group() avoid some of the usual balance conditions to allow it |
30ce5dab PZ |
7241 | * to create an effective group imbalance. |
7242 | * | |
7243 | * This is a somewhat tricky proposition since the next run might not find the | |
7244 | * group imbalance and decide the groups need to be balanced again. A most | |
7245 | * subtle and fragile situation. | |
7246 | */ | |
7247 | ||
6263322c | 7248 | static inline int sg_imbalanced(struct sched_group *group) |
30ce5dab | 7249 | { |
63b2ca30 | 7250 | return group->sgc->imbalance; |
30ce5dab PZ |
7251 | } |
7252 | ||
b37d9316 | 7253 | /* |
ea67821b VG |
7254 | * group_has_capacity returns true if the group has spare capacity that could |
7255 | * be used by some tasks. | |
7256 | * We consider that a group has spare capacity if the * number of task is | |
9e91d61d DE |
7257 | * smaller than the number of CPUs or if the utilization is lower than the |
7258 | * available capacity for CFS tasks. | |
ea67821b VG |
7259 | * For the latter, we use a threshold to stabilize the state, to take into |
7260 | * account the variance of the tasks' load and to return true if the available | |
7261 | * capacity in meaningful for the load balancer. | |
7262 | * As an example, an available capacity of 1% can appear but it doesn't make | |
7263 | * any benefit for the load balance. | |
b37d9316 | 7264 | */ |
ea67821b VG |
7265 | static inline bool |
7266 | group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs) | |
b37d9316 | 7267 | { |
ea67821b VG |
7268 | if (sgs->sum_nr_running < sgs->group_weight) |
7269 | return true; | |
c61037e9 | 7270 | |
ea67821b | 7271 | if ((sgs->group_capacity * 100) > |
9e91d61d | 7272 | (sgs->group_util * env->sd->imbalance_pct)) |
ea67821b | 7273 | return true; |
b37d9316 | 7274 | |
ea67821b VG |
7275 | return false; |
7276 | } | |
7277 | ||
7278 | /* | |
7279 | * group_is_overloaded returns true if the group has more tasks than it can | |
7280 | * handle. | |
7281 | * group_is_overloaded is not equals to !group_has_capacity because a group | |
7282 | * with the exact right number of tasks, has no more spare capacity but is not | |
7283 | * overloaded so both group_has_capacity and group_is_overloaded return | |
7284 | * false. | |
7285 | */ | |
7286 | static inline bool | |
7287 | group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs) | |
7288 | { | |
7289 | if (sgs->sum_nr_running <= sgs->group_weight) | |
7290 | return false; | |
b37d9316 | 7291 | |
ea67821b | 7292 | if ((sgs->group_capacity * 100) < |
9e91d61d | 7293 | (sgs->group_util * env->sd->imbalance_pct)) |
ea67821b | 7294 | return true; |
b37d9316 | 7295 | |
ea67821b | 7296 | return false; |
b37d9316 PZ |
7297 | } |
7298 | ||
9e0994c0 MR |
7299 | /* |
7300 | * group_smaller_cpu_capacity: Returns true if sched_group sg has smaller | |
7301 | * per-CPU capacity than sched_group ref. | |
7302 | */ | |
7303 | static inline bool | |
7304 | group_smaller_cpu_capacity(struct sched_group *sg, struct sched_group *ref) | |
7305 | { | |
7306 | return sg->sgc->min_capacity * capacity_margin < | |
7307 | ref->sgc->min_capacity * 1024; | |
7308 | } | |
7309 | ||
79a89f92 LY |
7310 | static inline enum |
7311 | group_type group_classify(struct sched_group *group, | |
7312 | struct sg_lb_stats *sgs) | |
caeb178c | 7313 | { |
ea67821b | 7314 | if (sgs->group_no_capacity) |
caeb178c RR |
7315 | return group_overloaded; |
7316 | ||
7317 | if (sg_imbalanced(group)) | |
7318 | return group_imbalanced; | |
7319 | ||
7320 | return group_other; | |
7321 | } | |
7322 | ||
1e3c88bd PZ |
7323 | /** |
7324 | * update_sg_lb_stats - Update sched_group's statistics for load balancing. | |
cd96891d | 7325 | * @env: The load balancing environment. |
1e3c88bd | 7326 | * @group: sched_group whose statistics are to be updated. |
1e3c88bd | 7327 | * @load_idx: Load index of sched_domain of this_cpu for load calc. |
1e3c88bd | 7328 | * @local_group: Does group contain this_cpu. |
1e3c88bd | 7329 | * @sgs: variable to hold the statistics for this group. |
cd3bd4e6 | 7330 | * @overload: Indicate more than one runnable task for any CPU. |
1e3c88bd | 7331 | */ |
bd939f45 PZ |
7332 | static inline void update_sg_lb_stats(struct lb_env *env, |
7333 | struct sched_group *group, int load_idx, | |
4486edd1 TC |
7334 | int local_group, struct sg_lb_stats *sgs, |
7335 | bool *overload) | |
1e3c88bd | 7336 | { |
30ce5dab | 7337 | unsigned long load; |
a426f99c | 7338 | int i, nr_running; |
1e3c88bd | 7339 | |
b72ff13c PZ |
7340 | memset(sgs, 0, sizeof(*sgs)); |
7341 | ||
b9403130 | 7342 | for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
1e3c88bd PZ |
7343 | struct rq *rq = cpu_rq(i); |
7344 | ||
1e3c88bd | 7345 | /* Bias balancing toward cpus of our domain */ |
6263322c | 7346 | if (local_group) |
04f733b4 | 7347 | load = target_load(i, load_idx); |
6263322c | 7348 | else |
1e3c88bd | 7349 | load = source_load(i, load_idx); |
1e3c88bd PZ |
7350 | |
7351 | sgs->group_load += load; | |
9e91d61d | 7352 | sgs->group_util += cpu_util(i); |
65fdac08 | 7353 | sgs->sum_nr_running += rq->cfs.h_nr_running; |
4486edd1 | 7354 | |
a426f99c WL |
7355 | nr_running = rq->nr_running; |
7356 | if (nr_running > 1) | |
4486edd1 TC |
7357 | *overload = true; |
7358 | ||
0ec8aa00 PZ |
7359 | #ifdef CONFIG_NUMA_BALANCING |
7360 | sgs->nr_numa_running += rq->nr_numa_running; | |
7361 | sgs->nr_preferred_running += rq->nr_preferred_running; | |
7362 | #endif | |
1e3c88bd | 7363 | sgs->sum_weighted_load += weighted_cpuload(i); |
a426f99c WL |
7364 | /* |
7365 | * No need to call idle_cpu() if nr_running is not 0 | |
7366 | */ | |
7367 | if (!nr_running && idle_cpu(i)) | |
aae6d3dd | 7368 | sgs->idle_cpus++; |
1e3c88bd PZ |
7369 | } |
7370 | ||
63b2ca30 NP |
7371 | /* Adjust by relative CPU capacity of the group */ |
7372 | sgs->group_capacity = group->sgc->capacity; | |
ca8ce3d0 | 7373 | sgs->avg_load = (sgs->group_load*SCHED_CAPACITY_SCALE) / sgs->group_capacity; |
1e3c88bd | 7374 | |
dd5feea1 | 7375 | if (sgs->sum_nr_running) |
38d0f770 | 7376 | sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; |
1e3c88bd | 7377 | |
aae6d3dd | 7378 | sgs->group_weight = group->group_weight; |
b37d9316 | 7379 | |
ea67821b | 7380 | sgs->group_no_capacity = group_is_overloaded(env, sgs); |
79a89f92 | 7381 | sgs->group_type = group_classify(group, sgs); |
1e3c88bd PZ |
7382 | } |
7383 | ||
532cb4c4 MN |
7384 | /** |
7385 | * update_sd_pick_busiest - return 1 on busiest group | |
cd96891d | 7386 | * @env: The load balancing environment. |
532cb4c4 MN |
7387 | * @sds: sched_domain statistics |
7388 | * @sg: sched_group candidate to be checked for being the busiest | |
b6b12294 | 7389 | * @sgs: sched_group statistics |
532cb4c4 MN |
7390 | * |
7391 | * Determine if @sg is a busier group than the previously selected | |
7392 | * busiest group. | |
e69f6186 YB |
7393 | * |
7394 | * Return: %true if @sg is a busier group than the previously selected | |
7395 | * busiest group. %false otherwise. | |
532cb4c4 | 7396 | */ |
bd939f45 | 7397 | static bool update_sd_pick_busiest(struct lb_env *env, |
532cb4c4 MN |
7398 | struct sd_lb_stats *sds, |
7399 | struct sched_group *sg, | |
bd939f45 | 7400 | struct sg_lb_stats *sgs) |
532cb4c4 | 7401 | { |
caeb178c | 7402 | struct sg_lb_stats *busiest = &sds->busiest_stat; |
532cb4c4 | 7403 | |
caeb178c | 7404 | if (sgs->group_type > busiest->group_type) |
532cb4c4 MN |
7405 | return true; |
7406 | ||
caeb178c RR |
7407 | if (sgs->group_type < busiest->group_type) |
7408 | return false; | |
7409 | ||
7410 | if (sgs->avg_load <= busiest->avg_load) | |
7411 | return false; | |
7412 | ||
9e0994c0 MR |
7413 | if (!(env->sd->flags & SD_ASYM_CPUCAPACITY)) |
7414 | goto asym_packing; | |
7415 | ||
7416 | /* | |
7417 | * Candidate sg has no more than one task per CPU and | |
7418 | * has higher per-CPU capacity. Migrating tasks to less | |
7419 | * capable CPUs may harm throughput. Maximize throughput, | |
7420 | * power/energy consequences are not considered. | |
7421 | */ | |
7422 | if (sgs->sum_nr_running <= sgs->group_weight && | |
7423 | group_smaller_cpu_capacity(sds->local, sg)) | |
7424 | return false; | |
7425 | ||
7426 | asym_packing: | |
caeb178c RR |
7427 | /* This is the busiest node in its class. */ |
7428 | if (!(env->sd->flags & SD_ASYM_PACKING)) | |
532cb4c4 MN |
7429 | return true; |
7430 | ||
1f621e02 SD |
7431 | /* No ASYM_PACKING if target cpu is already busy */ |
7432 | if (env->idle == CPU_NOT_IDLE) | |
7433 | return true; | |
532cb4c4 | 7434 | /* |
afe06efd TC |
7435 | * ASYM_PACKING needs to move all the work to the highest |
7436 | * prority CPUs in the group, therefore mark all groups | |
7437 | * of lower priority than ourself as busy. | |
532cb4c4 | 7438 | */ |
afe06efd TC |
7439 | if (sgs->sum_nr_running && |
7440 | sched_asym_prefer(env->dst_cpu, sg->asym_prefer_cpu)) { | |
532cb4c4 MN |
7441 | if (!sds->busiest) |
7442 | return true; | |
7443 | ||
afe06efd TC |
7444 | /* Prefer to move from lowest priority cpu's work */ |
7445 | if (sched_asym_prefer(sds->busiest->asym_prefer_cpu, | |
7446 | sg->asym_prefer_cpu)) | |
532cb4c4 MN |
7447 | return true; |
7448 | } | |
7449 | ||
7450 | return false; | |
7451 | } | |
7452 | ||
0ec8aa00 PZ |
7453 | #ifdef CONFIG_NUMA_BALANCING |
7454 | static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) | |
7455 | { | |
7456 | if (sgs->sum_nr_running > sgs->nr_numa_running) | |
7457 | return regular; | |
7458 | if (sgs->sum_nr_running > sgs->nr_preferred_running) | |
7459 | return remote; | |
7460 | return all; | |
7461 | } | |
7462 | ||
7463 | static inline enum fbq_type fbq_classify_rq(struct rq *rq) | |
7464 | { | |
7465 | if (rq->nr_running > rq->nr_numa_running) | |
7466 | return regular; | |
7467 | if (rq->nr_running > rq->nr_preferred_running) | |
7468 | return remote; | |
7469 | return all; | |
7470 | } | |
7471 | #else | |
7472 | static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) | |
7473 | { | |
7474 | return all; | |
7475 | } | |
7476 | ||
7477 | static inline enum fbq_type fbq_classify_rq(struct rq *rq) | |
7478 | { | |
7479 | return regular; | |
7480 | } | |
7481 | #endif /* CONFIG_NUMA_BALANCING */ | |
7482 | ||
1e3c88bd | 7483 | /** |
461819ac | 7484 | * update_sd_lb_stats - Update sched_domain's statistics for load balancing. |
cd96891d | 7485 | * @env: The load balancing environment. |
1e3c88bd PZ |
7486 | * @sds: variable to hold the statistics for this sched_domain. |
7487 | */ | |
0ec8aa00 | 7488 | static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds) |
1e3c88bd | 7489 | { |
bd939f45 PZ |
7490 | struct sched_domain *child = env->sd->child; |
7491 | struct sched_group *sg = env->sd->groups; | |
56cf515b | 7492 | struct sg_lb_stats tmp_sgs; |
1e3c88bd | 7493 | int load_idx, prefer_sibling = 0; |
4486edd1 | 7494 | bool overload = false; |
1e3c88bd PZ |
7495 | |
7496 | if (child && child->flags & SD_PREFER_SIBLING) | |
7497 | prefer_sibling = 1; | |
7498 | ||
bd939f45 | 7499 | load_idx = get_sd_load_idx(env->sd, env->idle); |
1e3c88bd PZ |
7500 | |
7501 | do { | |
56cf515b | 7502 | struct sg_lb_stats *sgs = &tmp_sgs; |
1e3c88bd PZ |
7503 | int local_group; |
7504 | ||
bd939f45 | 7505 | local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg)); |
56cf515b JK |
7506 | if (local_group) { |
7507 | sds->local = sg; | |
7508 | sgs = &sds->local_stat; | |
b72ff13c PZ |
7509 | |
7510 | if (env->idle != CPU_NEWLY_IDLE || | |
63b2ca30 NP |
7511 | time_after_eq(jiffies, sg->sgc->next_update)) |
7512 | update_group_capacity(env->sd, env->dst_cpu); | |
56cf515b | 7513 | } |
1e3c88bd | 7514 | |
4486edd1 TC |
7515 | update_sg_lb_stats(env, sg, load_idx, local_group, sgs, |
7516 | &overload); | |
1e3c88bd | 7517 | |
b72ff13c PZ |
7518 | if (local_group) |
7519 | goto next_group; | |
7520 | ||
1e3c88bd PZ |
7521 | /* |
7522 | * In case the child domain prefers tasks go to siblings | |
ea67821b | 7523 | * first, lower the sg capacity so that we'll try |
75dd321d NR |
7524 | * and move all the excess tasks away. We lower the capacity |
7525 | * of a group only if the local group has the capacity to fit | |
ea67821b VG |
7526 | * these excess tasks. The extra check prevents the case where |
7527 | * you always pull from the heaviest group when it is already | |
7528 | * under-utilized (possible with a large weight task outweighs | |
7529 | * the tasks on the system). | |
1e3c88bd | 7530 | */ |
b72ff13c | 7531 | if (prefer_sibling && sds->local && |
ea67821b VG |
7532 | group_has_capacity(env, &sds->local_stat) && |
7533 | (sgs->sum_nr_running > 1)) { | |
7534 | sgs->group_no_capacity = 1; | |
79a89f92 | 7535 | sgs->group_type = group_classify(sg, sgs); |
cb0b9f24 | 7536 | } |
1e3c88bd | 7537 | |
b72ff13c | 7538 | if (update_sd_pick_busiest(env, sds, sg, sgs)) { |
532cb4c4 | 7539 | sds->busiest = sg; |
56cf515b | 7540 | sds->busiest_stat = *sgs; |
1e3c88bd PZ |
7541 | } |
7542 | ||
b72ff13c PZ |
7543 | next_group: |
7544 | /* Now, start updating sd_lb_stats */ | |
7545 | sds->total_load += sgs->group_load; | |
63b2ca30 | 7546 | sds->total_capacity += sgs->group_capacity; |
b72ff13c | 7547 | |
532cb4c4 | 7548 | sg = sg->next; |
bd939f45 | 7549 | } while (sg != env->sd->groups); |
0ec8aa00 PZ |
7550 | |
7551 | if (env->sd->flags & SD_NUMA) | |
7552 | env->fbq_type = fbq_classify_group(&sds->busiest_stat); | |
4486edd1 TC |
7553 | |
7554 | if (!env->sd->parent) { | |
7555 | /* update overload indicator if we are at root domain */ | |
7556 | if (env->dst_rq->rd->overload != overload) | |
7557 | env->dst_rq->rd->overload = overload; | |
7558 | } | |
7559 | ||
532cb4c4 MN |
7560 | } |
7561 | ||
532cb4c4 MN |
7562 | /** |
7563 | * check_asym_packing - Check to see if the group is packed into the | |
7564 | * sched doman. | |
7565 | * | |
7566 | * This is primarily intended to used at the sibling level. Some | |
7567 | * cores like POWER7 prefer to use lower numbered SMT threads. In the | |
7568 | * case of POWER7, it can move to lower SMT modes only when higher | |
7569 | * threads are idle. When in lower SMT modes, the threads will | |
7570 | * perform better since they share less core resources. Hence when we | |
7571 | * have idle threads, we want them to be the higher ones. | |
7572 | * | |
7573 | * This packing function is run on idle threads. It checks to see if | |
7574 | * the busiest CPU in this domain (core in the P7 case) has a higher | |
7575 | * CPU number than the packing function is being run on. Here we are | |
7576 | * assuming lower CPU number will be equivalent to lower a SMT thread | |
7577 | * number. | |
7578 | * | |
e69f6186 | 7579 | * Return: 1 when packing is required and a task should be moved to |
b6b12294 MN |
7580 | * this CPU. The amount of the imbalance is returned in *imbalance. |
7581 | * | |
cd96891d | 7582 | * @env: The load balancing environment. |
532cb4c4 | 7583 | * @sds: Statistics of the sched_domain which is to be packed |
532cb4c4 | 7584 | */ |
bd939f45 | 7585 | static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) |
532cb4c4 MN |
7586 | { |
7587 | int busiest_cpu; | |
7588 | ||
bd939f45 | 7589 | if (!(env->sd->flags & SD_ASYM_PACKING)) |
532cb4c4 MN |
7590 | return 0; |
7591 | ||
1f621e02 SD |
7592 | if (env->idle == CPU_NOT_IDLE) |
7593 | return 0; | |
7594 | ||
532cb4c4 MN |
7595 | if (!sds->busiest) |
7596 | return 0; | |
7597 | ||
afe06efd TC |
7598 | busiest_cpu = sds->busiest->asym_prefer_cpu; |
7599 | if (sched_asym_prefer(busiest_cpu, env->dst_cpu)) | |
532cb4c4 MN |
7600 | return 0; |
7601 | ||
bd939f45 | 7602 | env->imbalance = DIV_ROUND_CLOSEST( |
63b2ca30 | 7603 | sds->busiest_stat.avg_load * sds->busiest_stat.group_capacity, |
ca8ce3d0 | 7604 | SCHED_CAPACITY_SCALE); |
bd939f45 | 7605 | |
532cb4c4 | 7606 | return 1; |
1e3c88bd PZ |
7607 | } |
7608 | ||
7609 | /** | |
7610 | * fix_small_imbalance - Calculate the minor imbalance that exists | |
7611 | * amongst the groups of a sched_domain, during | |
7612 | * load balancing. | |
cd96891d | 7613 | * @env: The load balancing environment. |
1e3c88bd | 7614 | * @sds: Statistics of the sched_domain whose imbalance is to be calculated. |
1e3c88bd | 7615 | */ |
bd939f45 PZ |
7616 | static inline |
7617 | void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) | |
1e3c88bd | 7618 | { |
63b2ca30 | 7619 | unsigned long tmp, capa_now = 0, capa_move = 0; |
1e3c88bd | 7620 | unsigned int imbn = 2; |
dd5feea1 | 7621 | unsigned long scaled_busy_load_per_task; |
56cf515b | 7622 | struct sg_lb_stats *local, *busiest; |
1e3c88bd | 7623 | |
56cf515b JK |
7624 | local = &sds->local_stat; |
7625 | busiest = &sds->busiest_stat; | |
1e3c88bd | 7626 | |
56cf515b JK |
7627 | if (!local->sum_nr_running) |
7628 | local->load_per_task = cpu_avg_load_per_task(env->dst_cpu); | |
7629 | else if (busiest->load_per_task > local->load_per_task) | |
7630 | imbn = 1; | |
dd5feea1 | 7631 | |
56cf515b | 7632 | scaled_busy_load_per_task = |
ca8ce3d0 | 7633 | (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
63b2ca30 | 7634 | busiest->group_capacity; |
56cf515b | 7635 | |
3029ede3 VD |
7636 | if (busiest->avg_load + scaled_busy_load_per_task >= |
7637 | local->avg_load + (scaled_busy_load_per_task * imbn)) { | |
56cf515b | 7638 | env->imbalance = busiest->load_per_task; |
1e3c88bd PZ |
7639 | return; |
7640 | } | |
7641 | ||
7642 | /* | |
7643 | * OK, we don't have enough imbalance to justify moving tasks, | |
ced549fa | 7644 | * however we may be able to increase total CPU capacity used by |
1e3c88bd PZ |
7645 | * moving them. |
7646 | */ | |
7647 | ||
63b2ca30 | 7648 | capa_now += busiest->group_capacity * |
56cf515b | 7649 | min(busiest->load_per_task, busiest->avg_load); |
63b2ca30 | 7650 | capa_now += local->group_capacity * |
56cf515b | 7651 | min(local->load_per_task, local->avg_load); |
ca8ce3d0 | 7652 | capa_now /= SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
7653 | |
7654 | /* Amount of load we'd subtract */ | |
a2cd4260 | 7655 | if (busiest->avg_load > scaled_busy_load_per_task) { |
63b2ca30 | 7656 | capa_move += busiest->group_capacity * |
56cf515b | 7657 | min(busiest->load_per_task, |
a2cd4260 | 7658 | busiest->avg_load - scaled_busy_load_per_task); |
56cf515b | 7659 | } |
1e3c88bd PZ |
7660 | |
7661 | /* Amount of load we'd add */ | |
63b2ca30 | 7662 | if (busiest->avg_load * busiest->group_capacity < |
ca8ce3d0 | 7663 | busiest->load_per_task * SCHED_CAPACITY_SCALE) { |
63b2ca30 NP |
7664 | tmp = (busiest->avg_load * busiest->group_capacity) / |
7665 | local->group_capacity; | |
56cf515b | 7666 | } else { |
ca8ce3d0 | 7667 | tmp = (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
63b2ca30 | 7668 | local->group_capacity; |
56cf515b | 7669 | } |
63b2ca30 | 7670 | capa_move += local->group_capacity * |
3ae11c90 | 7671 | min(local->load_per_task, local->avg_load + tmp); |
ca8ce3d0 | 7672 | capa_move /= SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
7673 | |
7674 | /* Move if we gain throughput */ | |
63b2ca30 | 7675 | if (capa_move > capa_now) |
56cf515b | 7676 | env->imbalance = busiest->load_per_task; |
1e3c88bd PZ |
7677 | } |
7678 | ||
7679 | /** | |
7680 | * calculate_imbalance - Calculate the amount of imbalance present within the | |
7681 | * groups of a given sched_domain during load balance. | |
bd939f45 | 7682 | * @env: load balance environment |
1e3c88bd | 7683 | * @sds: statistics of the sched_domain whose imbalance is to be calculated. |
1e3c88bd | 7684 | */ |
bd939f45 | 7685 | static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds) |
1e3c88bd | 7686 | { |
dd5feea1 | 7687 | unsigned long max_pull, load_above_capacity = ~0UL; |
56cf515b JK |
7688 | struct sg_lb_stats *local, *busiest; |
7689 | ||
7690 | local = &sds->local_stat; | |
56cf515b | 7691 | busiest = &sds->busiest_stat; |
dd5feea1 | 7692 | |
caeb178c | 7693 | if (busiest->group_type == group_imbalanced) { |
30ce5dab PZ |
7694 | /* |
7695 | * In the group_imb case we cannot rely on group-wide averages | |
7696 | * to ensure cpu-load equilibrium, look at wider averages. XXX | |
7697 | */ | |
56cf515b JK |
7698 | busiest->load_per_task = |
7699 | min(busiest->load_per_task, sds->avg_load); | |
dd5feea1 SS |
7700 | } |
7701 | ||
1e3c88bd | 7702 | /* |
885e542c DE |
7703 | * Avg load of busiest sg can be less and avg load of local sg can |
7704 | * be greater than avg load across all sgs of sd because avg load | |
7705 | * factors in sg capacity and sgs with smaller group_type are | |
7706 | * skipped when updating the busiest sg: | |
1e3c88bd | 7707 | */ |
b1885550 VD |
7708 | if (busiest->avg_load <= sds->avg_load || |
7709 | local->avg_load >= sds->avg_load) { | |
bd939f45 PZ |
7710 | env->imbalance = 0; |
7711 | return fix_small_imbalance(env, sds); | |
1e3c88bd PZ |
7712 | } |
7713 | ||
9a5d9ba6 PZ |
7714 | /* |
7715 | * If there aren't any idle cpus, avoid creating some. | |
7716 | */ | |
7717 | if (busiest->group_type == group_overloaded && | |
7718 | local->group_type == group_overloaded) { | |
1be0eb2a | 7719 | load_above_capacity = busiest->sum_nr_running * SCHED_CAPACITY_SCALE; |
cfa10334 | 7720 | if (load_above_capacity > busiest->group_capacity) { |
ea67821b | 7721 | load_above_capacity -= busiest->group_capacity; |
26656215 | 7722 | load_above_capacity *= scale_load_down(NICE_0_LOAD); |
cfa10334 MR |
7723 | load_above_capacity /= busiest->group_capacity; |
7724 | } else | |
ea67821b | 7725 | load_above_capacity = ~0UL; |
dd5feea1 SS |
7726 | } |
7727 | ||
7728 | /* | |
7729 | * We're trying to get all the cpus to the average_load, so we don't | |
7730 | * want to push ourselves above the average load, nor do we wish to | |
7731 | * reduce the max loaded cpu below the average load. At the same time, | |
0a9b23ce DE |
7732 | * we also don't want to reduce the group load below the group |
7733 | * capacity. Thus we look for the minimum possible imbalance. | |
dd5feea1 | 7734 | */ |
30ce5dab | 7735 | max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity); |
1e3c88bd PZ |
7736 | |
7737 | /* How much load to actually move to equalise the imbalance */ | |
56cf515b | 7738 | env->imbalance = min( |
63b2ca30 NP |
7739 | max_pull * busiest->group_capacity, |
7740 | (sds->avg_load - local->avg_load) * local->group_capacity | |
ca8ce3d0 | 7741 | ) / SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
7742 | |
7743 | /* | |
7744 | * if *imbalance is less than the average load per runnable task | |
25985edc | 7745 | * there is no guarantee that any tasks will be moved so we'll have |
1e3c88bd PZ |
7746 | * a think about bumping its value to force at least one task to be |
7747 | * moved | |
7748 | */ | |
56cf515b | 7749 | if (env->imbalance < busiest->load_per_task) |
bd939f45 | 7750 | return fix_small_imbalance(env, sds); |
1e3c88bd | 7751 | } |
fab47622 | 7752 | |
1e3c88bd PZ |
7753 | /******* find_busiest_group() helpers end here *********************/ |
7754 | ||
7755 | /** | |
7756 | * find_busiest_group - Returns the busiest group within the sched_domain | |
0a9b23ce | 7757 | * if there is an imbalance. |
1e3c88bd PZ |
7758 | * |
7759 | * Also calculates the amount of weighted load which should be moved | |
7760 | * to restore balance. | |
7761 | * | |
cd96891d | 7762 | * @env: The load balancing environment. |
1e3c88bd | 7763 | * |
e69f6186 | 7764 | * Return: - The busiest group if imbalance exists. |
1e3c88bd | 7765 | */ |
56cf515b | 7766 | static struct sched_group *find_busiest_group(struct lb_env *env) |
1e3c88bd | 7767 | { |
56cf515b | 7768 | struct sg_lb_stats *local, *busiest; |
1e3c88bd PZ |
7769 | struct sd_lb_stats sds; |
7770 | ||
147c5fc2 | 7771 | init_sd_lb_stats(&sds); |
1e3c88bd PZ |
7772 | |
7773 | /* | |
7774 | * Compute the various statistics relavent for load balancing at | |
7775 | * this level. | |
7776 | */ | |
23f0d209 | 7777 | update_sd_lb_stats(env, &sds); |
56cf515b JK |
7778 | local = &sds.local_stat; |
7779 | busiest = &sds.busiest_stat; | |
1e3c88bd | 7780 | |
ea67821b | 7781 | /* ASYM feature bypasses nice load balance check */ |
1f621e02 | 7782 | if (check_asym_packing(env, &sds)) |
532cb4c4 MN |
7783 | return sds.busiest; |
7784 | ||
cc57aa8f | 7785 | /* There is no busy sibling group to pull tasks from */ |
56cf515b | 7786 | if (!sds.busiest || busiest->sum_nr_running == 0) |
1e3c88bd PZ |
7787 | goto out_balanced; |
7788 | ||
ca8ce3d0 NP |
7789 | sds.avg_load = (SCHED_CAPACITY_SCALE * sds.total_load) |
7790 | / sds.total_capacity; | |
b0432d8f | 7791 | |
866ab43e PZ |
7792 | /* |
7793 | * If the busiest group is imbalanced the below checks don't | |
30ce5dab | 7794 | * work because they assume all things are equal, which typically |
866ab43e PZ |
7795 | * isn't true due to cpus_allowed constraints and the like. |
7796 | */ | |
caeb178c | 7797 | if (busiest->group_type == group_imbalanced) |
866ab43e PZ |
7798 | goto force_balance; |
7799 | ||
cc57aa8f | 7800 | /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */ |
ea67821b VG |
7801 | if (env->idle == CPU_NEWLY_IDLE && group_has_capacity(env, local) && |
7802 | busiest->group_no_capacity) | |
fab47622 NR |
7803 | goto force_balance; |
7804 | ||
cc57aa8f | 7805 | /* |
9c58c79a | 7806 | * If the local group is busier than the selected busiest group |
cc57aa8f PZ |
7807 | * don't try and pull any tasks. |
7808 | */ | |
56cf515b | 7809 | if (local->avg_load >= busiest->avg_load) |
1e3c88bd PZ |
7810 | goto out_balanced; |
7811 | ||
cc57aa8f PZ |
7812 | /* |
7813 | * Don't pull any tasks if this group is already above the domain | |
7814 | * average load. | |
7815 | */ | |
56cf515b | 7816 | if (local->avg_load >= sds.avg_load) |
1e3c88bd PZ |
7817 | goto out_balanced; |
7818 | ||
bd939f45 | 7819 | if (env->idle == CPU_IDLE) { |
aae6d3dd | 7820 | /* |
43f4d666 VG |
7821 | * This cpu is idle. If the busiest group is not overloaded |
7822 | * and there is no imbalance between this and busiest group | |
7823 | * wrt idle cpus, it is balanced. The imbalance becomes | |
7824 | * significant if the diff is greater than 1 otherwise we | |
7825 | * might end up to just move the imbalance on another group | |
aae6d3dd | 7826 | */ |
43f4d666 VG |
7827 | if ((busiest->group_type != group_overloaded) && |
7828 | (local->idle_cpus <= (busiest->idle_cpus + 1))) | |
aae6d3dd | 7829 | goto out_balanced; |
c186fafe PZ |
7830 | } else { |
7831 | /* | |
7832 | * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use | |
7833 | * imbalance_pct to be conservative. | |
7834 | */ | |
56cf515b JK |
7835 | if (100 * busiest->avg_load <= |
7836 | env->sd->imbalance_pct * local->avg_load) | |
c186fafe | 7837 | goto out_balanced; |
aae6d3dd | 7838 | } |
1e3c88bd | 7839 | |
fab47622 | 7840 | force_balance: |
1e3c88bd | 7841 | /* Looks like there is an imbalance. Compute it */ |
bd939f45 | 7842 | calculate_imbalance(env, &sds); |
1e3c88bd PZ |
7843 | return sds.busiest; |
7844 | ||
7845 | out_balanced: | |
bd939f45 | 7846 | env->imbalance = 0; |
1e3c88bd PZ |
7847 | return NULL; |
7848 | } | |
7849 | ||
7850 | /* | |
7851 | * find_busiest_queue - find the busiest runqueue among the cpus in group. | |
7852 | */ | |
bd939f45 | 7853 | static struct rq *find_busiest_queue(struct lb_env *env, |
b9403130 | 7854 | struct sched_group *group) |
1e3c88bd PZ |
7855 | { |
7856 | struct rq *busiest = NULL, *rq; | |
ced549fa | 7857 | unsigned long busiest_load = 0, busiest_capacity = 1; |
1e3c88bd PZ |
7858 | int i; |
7859 | ||
6906a408 | 7860 | for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
ea67821b | 7861 | unsigned long capacity, wl; |
0ec8aa00 PZ |
7862 | enum fbq_type rt; |
7863 | ||
7864 | rq = cpu_rq(i); | |
7865 | rt = fbq_classify_rq(rq); | |
1e3c88bd | 7866 | |
0ec8aa00 PZ |
7867 | /* |
7868 | * We classify groups/runqueues into three groups: | |
7869 | * - regular: there are !numa tasks | |
7870 | * - remote: there are numa tasks that run on the 'wrong' node | |
7871 | * - all: there is no distinction | |
7872 | * | |
7873 | * In order to avoid migrating ideally placed numa tasks, | |
7874 | * ignore those when there's better options. | |
7875 | * | |
7876 | * If we ignore the actual busiest queue to migrate another | |
7877 | * task, the next balance pass can still reduce the busiest | |
7878 | * queue by moving tasks around inside the node. | |
7879 | * | |
7880 | * If we cannot move enough load due to this classification | |
7881 | * the next pass will adjust the group classification and | |
7882 | * allow migration of more tasks. | |
7883 | * | |
7884 | * Both cases only affect the total convergence complexity. | |
7885 | */ | |
7886 | if (rt > env->fbq_type) | |
7887 | continue; | |
7888 | ||
ced549fa | 7889 | capacity = capacity_of(i); |
9d5efe05 | 7890 | |
6e40f5bb | 7891 | wl = weighted_cpuload(i); |
1e3c88bd | 7892 | |
6e40f5bb TG |
7893 | /* |
7894 | * When comparing with imbalance, use weighted_cpuload() | |
ced549fa | 7895 | * which is not scaled with the cpu capacity. |
6e40f5bb | 7896 | */ |
ea67821b VG |
7897 | |
7898 | if (rq->nr_running == 1 && wl > env->imbalance && | |
7899 | !check_cpu_capacity(rq, env->sd)) | |
1e3c88bd PZ |
7900 | continue; |
7901 | ||
6e40f5bb TG |
7902 | /* |
7903 | * For the load comparisons with the other cpu's, consider | |
ced549fa NP |
7904 | * the weighted_cpuload() scaled with the cpu capacity, so |
7905 | * that the load can be moved away from the cpu that is | |
7906 | * potentially running at a lower capacity. | |
95a79b80 | 7907 | * |
ced549fa | 7908 | * Thus we're looking for max(wl_i / capacity_i), crosswise |
95a79b80 | 7909 | * multiplication to rid ourselves of the division works out |
ced549fa NP |
7910 | * to: wl_i * capacity_j > wl_j * capacity_i; where j is |
7911 | * our previous maximum. | |
6e40f5bb | 7912 | */ |
ced549fa | 7913 | if (wl * busiest_capacity > busiest_load * capacity) { |
95a79b80 | 7914 | busiest_load = wl; |
ced549fa | 7915 | busiest_capacity = capacity; |
1e3c88bd PZ |
7916 | busiest = rq; |
7917 | } | |
7918 | } | |
7919 | ||
7920 | return busiest; | |
7921 | } | |
7922 | ||
7923 | /* | |
7924 | * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but | |
7925 | * so long as it is large enough. | |
7926 | */ | |
7927 | #define MAX_PINNED_INTERVAL 512 | |
7928 | ||
bd939f45 | 7929 | static int need_active_balance(struct lb_env *env) |
1af3ed3d | 7930 | { |
bd939f45 PZ |
7931 | struct sched_domain *sd = env->sd; |
7932 | ||
7933 | if (env->idle == CPU_NEWLY_IDLE) { | |
532cb4c4 MN |
7934 | |
7935 | /* | |
7936 | * ASYM_PACKING needs to force migrate tasks from busy but | |
afe06efd TC |
7937 | * lower priority CPUs in order to pack all tasks in the |
7938 | * highest priority CPUs. | |
532cb4c4 | 7939 | */ |
afe06efd TC |
7940 | if ((sd->flags & SD_ASYM_PACKING) && |
7941 | sched_asym_prefer(env->dst_cpu, env->src_cpu)) | |
532cb4c4 | 7942 | return 1; |
1af3ed3d PZ |
7943 | } |
7944 | ||
1aaf90a4 VG |
7945 | /* |
7946 | * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task. | |
7947 | * It's worth migrating the task if the src_cpu's capacity is reduced | |
7948 | * because of other sched_class or IRQs if more capacity stays | |
7949 | * available on dst_cpu. | |
7950 | */ | |
7951 | if ((env->idle != CPU_NOT_IDLE) && | |
7952 | (env->src_rq->cfs.h_nr_running == 1)) { | |
7953 | if ((check_cpu_capacity(env->src_rq, sd)) && | |
7954 | (capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100)) | |
7955 | return 1; | |
7956 | } | |
7957 | ||
1af3ed3d PZ |
7958 | return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2); |
7959 | } | |
7960 | ||
969c7921 TH |
7961 | static int active_load_balance_cpu_stop(void *data); |
7962 | ||
23f0d209 JK |
7963 | static int should_we_balance(struct lb_env *env) |
7964 | { | |
7965 | struct sched_group *sg = env->sd->groups; | |
7966 | struct cpumask *sg_cpus, *sg_mask; | |
7967 | int cpu, balance_cpu = -1; | |
7968 | ||
7969 | /* | |
7970 | * In the newly idle case, we will allow all the cpu's | |
7971 | * to do the newly idle load balance. | |
7972 | */ | |
7973 | if (env->idle == CPU_NEWLY_IDLE) | |
7974 | return 1; | |
7975 | ||
7976 | sg_cpus = sched_group_cpus(sg); | |
7977 | sg_mask = sched_group_mask(sg); | |
7978 | /* Try to find first idle cpu */ | |
7979 | for_each_cpu_and(cpu, sg_cpus, env->cpus) { | |
7980 | if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu)) | |
7981 | continue; | |
7982 | ||
7983 | balance_cpu = cpu; | |
7984 | break; | |
7985 | } | |
7986 | ||
7987 | if (balance_cpu == -1) | |
7988 | balance_cpu = group_balance_cpu(sg); | |
7989 | ||
7990 | /* | |
7991 | * First idle cpu or the first cpu(busiest) in this sched group | |
7992 | * is eligible for doing load balancing at this and above domains. | |
7993 | */ | |
b0cff9d8 | 7994 | return balance_cpu == env->dst_cpu; |
23f0d209 JK |
7995 | } |
7996 | ||
1e3c88bd PZ |
7997 | /* |
7998 | * Check this_cpu to ensure it is balanced within domain. Attempt to move | |
7999 | * tasks if there is an imbalance. | |
8000 | */ | |
8001 | static int load_balance(int this_cpu, struct rq *this_rq, | |
8002 | struct sched_domain *sd, enum cpu_idle_type idle, | |
23f0d209 | 8003 | int *continue_balancing) |
1e3c88bd | 8004 | { |
88b8dac0 | 8005 | int ld_moved, cur_ld_moved, active_balance = 0; |
6263322c | 8006 | struct sched_domain *sd_parent = sd->parent; |
1e3c88bd | 8007 | struct sched_group *group; |
1e3c88bd PZ |
8008 | struct rq *busiest; |
8009 | unsigned long flags; | |
4ba29684 | 8010 | struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask); |
1e3c88bd | 8011 | |
8e45cb54 PZ |
8012 | struct lb_env env = { |
8013 | .sd = sd, | |
ddcdf6e7 PZ |
8014 | .dst_cpu = this_cpu, |
8015 | .dst_rq = this_rq, | |
88b8dac0 | 8016 | .dst_grpmask = sched_group_cpus(sd->groups), |
8e45cb54 | 8017 | .idle = idle, |
eb95308e | 8018 | .loop_break = sched_nr_migrate_break, |
b9403130 | 8019 | .cpus = cpus, |
0ec8aa00 | 8020 | .fbq_type = all, |
163122b7 | 8021 | .tasks = LIST_HEAD_INIT(env.tasks), |
8e45cb54 PZ |
8022 | }; |
8023 | ||
cfc03118 JK |
8024 | /* |
8025 | * For NEWLY_IDLE load_balancing, we don't need to consider | |
8026 | * other cpus in our group | |
8027 | */ | |
e02e60c1 | 8028 | if (idle == CPU_NEWLY_IDLE) |
cfc03118 | 8029 | env.dst_grpmask = NULL; |
cfc03118 | 8030 | |
1e3c88bd PZ |
8031 | cpumask_copy(cpus, cpu_active_mask); |
8032 | ||
ae92882e | 8033 | schedstat_inc(sd->lb_count[idle]); |
1e3c88bd PZ |
8034 | |
8035 | redo: | |
23f0d209 JK |
8036 | if (!should_we_balance(&env)) { |
8037 | *continue_balancing = 0; | |
1e3c88bd | 8038 | goto out_balanced; |
23f0d209 | 8039 | } |
1e3c88bd | 8040 | |
23f0d209 | 8041 | group = find_busiest_group(&env); |
1e3c88bd | 8042 | if (!group) { |
ae92882e | 8043 | schedstat_inc(sd->lb_nobusyg[idle]); |
1e3c88bd PZ |
8044 | goto out_balanced; |
8045 | } | |
8046 | ||
b9403130 | 8047 | busiest = find_busiest_queue(&env, group); |
1e3c88bd | 8048 | if (!busiest) { |
ae92882e | 8049 | schedstat_inc(sd->lb_nobusyq[idle]); |
1e3c88bd PZ |
8050 | goto out_balanced; |
8051 | } | |
8052 | ||
78feefc5 | 8053 | BUG_ON(busiest == env.dst_rq); |
1e3c88bd | 8054 | |
ae92882e | 8055 | schedstat_add(sd->lb_imbalance[idle], env.imbalance); |
1e3c88bd | 8056 | |
1aaf90a4 VG |
8057 | env.src_cpu = busiest->cpu; |
8058 | env.src_rq = busiest; | |
8059 | ||
1e3c88bd PZ |
8060 | ld_moved = 0; |
8061 | if (busiest->nr_running > 1) { | |
8062 | /* | |
8063 | * Attempt to move tasks. If find_busiest_group has found | |
8064 | * an imbalance but busiest->nr_running <= 1, the group is | |
8065 | * still unbalanced. ld_moved simply stays zero, so it is | |
8066 | * correctly treated as an imbalance. | |
8067 | */ | |
8e45cb54 | 8068 | env.flags |= LBF_ALL_PINNED; |
c82513e5 | 8069 | env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running); |
8e45cb54 | 8070 | |
5d6523eb | 8071 | more_balance: |
163122b7 | 8072 | raw_spin_lock_irqsave(&busiest->lock, flags); |
88b8dac0 SV |
8073 | |
8074 | /* | |
8075 | * cur_ld_moved - load moved in current iteration | |
8076 | * ld_moved - cumulative load moved across iterations | |
8077 | */ | |
163122b7 | 8078 | cur_ld_moved = detach_tasks(&env); |
1e3c88bd PZ |
8079 | |
8080 | /* | |
163122b7 KT |
8081 | * We've detached some tasks from busiest_rq. Every |
8082 | * task is masked "TASK_ON_RQ_MIGRATING", so we can safely | |
8083 | * unlock busiest->lock, and we are able to be sure | |
8084 | * that nobody can manipulate the tasks in parallel. | |
8085 | * See task_rq_lock() family for the details. | |
1e3c88bd | 8086 | */ |
163122b7 KT |
8087 | |
8088 | raw_spin_unlock(&busiest->lock); | |
8089 | ||
8090 | if (cur_ld_moved) { | |
8091 | attach_tasks(&env); | |
8092 | ld_moved += cur_ld_moved; | |
8093 | } | |
8094 | ||
1e3c88bd | 8095 | local_irq_restore(flags); |
88b8dac0 | 8096 | |
f1cd0858 JK |
8097 | if (env.flags & LBF_NEED_BREAK) { |
8098 | env.flags &= ~LBF_NEED_BREAK; | |
8099 | goto more_balance; | |
8100 | } | |
8101 | ||
88b8dac0 SV |
8102 | /* |
8103 | * Revisit (affine) tasks on src_cpu that couldn't be moved to | |
8104 | * us and move them to an alternate dst_cpu in our sched_group | |
8105 | * where they can run. The upper limit on how many times we | |
8106 | * iterate on same src_cpu is dependent on number of cpus in our | |
8107 | * sched_group. | |
8108 | * | |
8109 | * This changes load balance semantics a bit on who can move | |
8110 | * load to a given_cpu. In addition to the given_cpu itself | |
8111 | * (or a ilb_cpu acting on its behalf where given_cpu is | |
8112 | * nohz-idle), we now have balance_cpu in a position to move | |
8113 | * load to given_cpu. In rare situations, this may cause | |
8114 | * conflicts (balance_cpu and given_cpu/ilb_cpu deciding | |
8115 | * _independently_ and at _same_ time to move some load to | |
8116 | * given_cpu) causing exceess load to be moved to given_cpu. | |
8117 | * This however should not happen so much in practice and | |
8118 | * moreover subsequent load balance cycles should correct the | |
8119 | * excess load moved. | |
8120 | */ | |
6263322c | 8121 | if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) { |
88b8dac0 | 8122 | |
7aff2e3a VD |
8123 | /* Prevent to re-select dst_cpu via env's cpus */ |
8124 | cpumask_clear_cpu(env.dst_cpu, env.cpus); | |
8125 | ||
78feefc5 | 8126 | env.dst_rq = cpu_rq(env.new_dst_cpu); |
88b8dac0 | 8127 | env.dst_cpu = env.new_dst_cpu; |
6263322c | 8128 | env.flags &= ~LBF_DST_PINNED; |
88b8dac0 SV |
8129 | env.loop = 0; |
8130 | env.loop_break = sched_nr_migrate_break; | |
e02e60c1 | 8131 | |
88b8dac0 SV |
8132 | /* |
8133 | * Go back to "more_balance" rather than "redo" since we | |
8134 | * need to continue with same src_cpu. | |
8135 | */ | |
8136 | goto more_balance; | |
8137 | } | |
1e3c88bd | 8138 | |
6263322c PZ |
8139 | /* |
8140 | * We failed to reach balance because of affinity. | |
8141 | */ | |
8142 | if (sd_parent) { | |
63b2ca30 | 8143 | int *group_imbalance = &sd_parent->groups->sgc->imbalance; |
6263322c | 8144 | |
afdeee05 | 8145 | if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) |
6263322c | 8146 | *group_imbalance = 1; |
6263322c PZ |
8147 | } |
8148 | ||
1e3c88bd | 8149 | /* All tasks on this runqueue were pinned by CPU affinity */ |
8e45cb54 | 8150 | if (unlikely(env.flags & LBF_ALL_PINNED)) { |
1e3c88bd | 8151 | cpumask_clear_cpu(cpu_of(busiest), cpus); |
bbf18b19 PN |
8152 | if (!cpumask_empty(cpus)) { |
8153 | env.loop = 0; | |
8154 | env.loop_break = sched_nr_migrate_break; | |
1e3c88bd | 8155 | goto redo; |
bbf18b19 | 8156 | } |
afdeee05 | 8157 | goto out_all_pinned; |
1e3c88bd PZ |
8158 | } |
8159 | } | |
8160 | ||
8161 | if (!ld_moved) { | |
ae92882e | 8162 | schedstat_inc(sd->lb_failed[idle]); |
58b26c4c VP |
8163 | /* |
8164 | * Increment the failure counter only on periodic balance. | |
8165 | * We do not want newidle balance, which can be very | |
8166 | * frequent, pollute the failure counter causing | |
8167 | * excessive cache_hot migrations and active balances. | |
8168 | */ | |
8169 | if (idle != CPU_NEWLY_IDLE) | |
8170 | sd->nr_balance_failed++; | |
1e3c88bd | 8171 | |
bd939f45 | 8172 | if (need_active_balance(&env)) { |
1e3c88bd PZ |
8173 | raw_spin_lock_irqsave(&busiest->lock, flags); |
8174 | ||
969c7921 TH |
8175 | /* don't kick the active_load_balance_cpu_stop, |
8176 | * if the curr task on busiest cpu can't be | |
8177 | * moved to this_cpu | |
1e3c88bd PZ |
8178 | */ |
8179 | if (!cpumask_test_cpu(this_cpu, | |
fa17b507 | 8180 | tsk_cpus_allowed(busiest->curr))) { |
1e3c88bd PZ |
8181 | raw_spin_unlock_irqrestore(&busiest->lock, |
8182 | flags); | |
8e45cb54 | 8183 | env.flags |= LBF_ALL_PINNED; |
1e3c88bd PZ |
8184 | goto out_one_pinned; |
8185 | } | |
8186 | ||
969c7921 TH |
8187 | /* |
8188 | * ->active_balance synchronizes accesses to | |
8189 | * ->active_balance_work. Once set, it's cleared | |
8190 | * only after active load balance is finished. | |
8191 | */ | |
1e3c88bd PZ |
8192 | if (!busiest->active_balance) { |
8193 | busiest->active_balance = 1; | |
8194 | busiest->push_cpu = this_cpu; | |
8195 | active_balance = 1; | |
8196 | } | |
8197 | raw_spin_unlock_irqrestore(&busiest->lock, flags); | |
969c7921 | 8198 | |
bd939f45 | 8199 | if (active_balance) { |
969c7921 TH |
8200 | stop_one_cpu_nowait(cpu_of(busiest), |
8201 | active_load_balance_cpu_stop, busiest, | |
8202 | &busiest->active_balance_work); | |
bd939f45 | 8203 | } |
1e3c88bd | 8204 | |
d02c0711 | 8205 | /* We've kicked active balancing, force task migration. */ |
1e3c88bd PZ |
8206 | sd->nr_balance_failed = sd->cache_nice_tries+1; |
8207 | } | |
8208 | } else | |
8209 | sd->nr_balance_failed = 0; | |
8210 | ||
8211 | if (likely(!active_balance)) { | |
8212 | /* We were unbalanced, so reset the balancing interval */ | |
8213 | sd->balance_interval = sd->min_interval; | |
8214 | } else { | |
8215 | /* | |
8216 | * If we've begun active balancing, start to back off. This | |
8217 | * case may not be covered by the all_pinned logic if there | |
8218 | * is only 1 task on the busy runqueue (because we don't call | |
163122b7 | 8219 | * detach_tasks). |
1e3c88bd PZ |
8220 | */ |
8221 | if (sd->balance_interval < sd->max_interval) | |
8222 | sd->balance_interval *= 2; | |
8223 | } | |
8224 | ||
1e3c88bd PZ |
8225 | goto out; |
8226 | ||
8227 | out_balanced: | |
afdeee05 VG |
8228 | /* |
8229 | * We reach balance although we may have faced some affinity | |
8230 | * constraints. Clear the imbalance flag if it was set. | |
8231 | */ | |
8232 | if (sd_parent) { | |
8233 | int *group_imbalance = &sd_parent->groups->sgc->imbalance; | |
8234 | ||
8235 | if (*group_imbalance) | |
8236 | *group_imbalance = 0; | |
8237 | } | |
8238 | ||
8239 | out_all_pinned: | |
8240 | /* | |
8241 | * We reach balance because all tasks are pinned at this level so | |
8242 | * we can't migrate them. Let the imbalance flag set so parent level | |
8243 | * can try to migrate them. | |
8244 | */ | |
ae92882e | 8245 | schedstat_inc(sd->lb_balanced[idle]); |
1e3c88bd PZ |
8246 | |
8247 | sd->nr_balance_failed = 0; | |
8248 | ||
8249 | out_one_pinned: | |
8250 | /* tune up the balancing interval */ | |
8e45cb54 | 8251 | if (((env.flags & LBF_ALL_PINNED) && |
5b54b56b | 8252 | sd->balance_interval < MAX_PINNED_INTERVAL) || |
1e3c88bd PZ |
8253 | (sd->balance_interval < sd->max_interval)) |
8254 | sd->balance_interval *= 2; | |
8255 | ||
46e49b38 | 8256 | ld_moved = 0; |
1e3c88bd | 8257 | out: |
1e3c88bd PZ |
8258 | return ld_moved; |
8259 | } | |
8260 | ||
52a08ef1 JL |
8261 | static inline unsigned long |
8262 | get_sd_balance_interval(struct sched_domain *sd, int cpu_busy) | |
8263 | { | |
8264 | unsigned long interval = sd->balance_interval; | |
8265 | ||
8266 | if (cpu_busy) | |
8267 | interval *= sd->busy_factor; | |
8268 | ||
8269 | /* scale ms to jiffies */ | |
8270 | interval = msecs_to_jiffies(interval); | |
8271 | interval = clamp(interval, 1UL, max_load_balance_interval); | |
8272 | ||
8273 | return interval; | |
8274 | } | |
8275 | ||
8276 | static inline void | |
31851a98 | 8277 | update_next_balance(struct sched_domain *sd, unsigned long *next_balance) |
52a08ef1 JL |
8278 | { |
8279 | unsigned long interval, next; | |
8280 | ||
31851a98 LY |
8281 | /* used by idle balance, so cpu_busy = 0 */ |
8282 | interval = get_sd_balance_interval(sd, 0); | |
52a08ef1 JL |
8283 | next = sd->last_balance + interval; |
8284 | ||
8285 | if (time_after(*next_balance, next)) | |
8286 | *next_balance = next; | |
8287 | } | |
8288 | ||
1e3c88bd PZ |
8289 | /* |
8290 | * idle_balance is called by schedule() if this_cpu is about to become | |
8291 | * idle. Attempts to pull tasks from other CPUs. | |
8292 | */ | |
46f69fa3 | 8293 | static int idle_balance(struct rq *this_rq, struct rq_flags *rf) |
1e3c88bd | 8294 | { |
52a08ef1 JL |
8295 | unsigned long next_balance = jiffies + HZ; |
8296 | int this_cpu = this_rq->cpu; | |
1e3c88bd PZ |
8297 | struct sched_domain *sd; |
8298 | int pulled_task = 0; | |
9bd721c5 | 8299 | u64 curr_cost = 0; |
1e3c88bd | 8300 | |
6e83125c PZ |
8301 | /* |
8302 | * We must set idle_stamp _before_ calling idle_balance(), such that we | |
8303 | * measure the duration of idle_balance() as idle time. | |
8304 | */ | |
8305 | this_rq->idle_stamp = rq_clock(this_rq); | |
8306 | ||
46f69fa3 MF |
8307 | /* |
8308 | * This is OK, because current is on_cpu, which avoids it being picked | |
8309 | * for load-balance and preemption/IRQs are still disabled avoiding | |
8310 | * further scheduler activity on it and we're being very careful to | |
8311 | * re-start the picking loop. | |
8312 | */ | |
8313 | rq_unpin_lock(this_rq, rf); | |
8314 | ||
4486edd1 TC |
8315 | if (this_rq->avg_idle < sysctl_sched_migration_cost || |
8316 | !this_rq->rd->overload) { | |
52a08ef1 JL |
8317 | rcu_read_lock(); |
8318 | sd = rcu_dereference_check_sched_domain(this_rq->sd); | |
8319 | if (sd) | |
31851a98 | 8320 | update_next_balance(sd, &next_balance); |
52a08ef1 JL |
8321 | rcu_read_unlock(); |
8322 | ||
6e83125c | 8323 | goto out; |
52a08ef1 | 8324 | } |
1e3c88bd | 8325 | |
f492e12e PZ |
8326 | raw_spin_unlock(&this_rq->lock); |
8327 | ||
48a16753 | 8328 | update_blocked_averages(this_cpu); |
dce840a0 | 8329 | rcu_read_lock(); |
1e3c88bd | 8330 | for_each_domain(this_cpu, sd) { |
23f0d209 | 8331 | int continue_balancing = 1; |
9bd721c5 | 8332 | u64 t0, domain_cost; |
1e3c88bd PZ |
8333 | |
8334 | if (!(sd->flags & SD_LOAD_BALANCE)) | |
8335 | continue; | |
8336 | ||
52a08ef1 | 8337 | if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) { |
31851a98 | 8338 | update_next_balance(sd, &next_balance); |
9bd721c5 | 8339 | break; |
52a08ef1 | 8340 | } |
9bd721c5 | 8341 | |
f492e12e | 8342 | if (sd->flags & SD_BALANCE_NEWIDLE) { |
9bd721c5 JL |
8343 | t0 = sched_clock_cpu(this_cpu); |
8344 | ||
f492e12e | 8345 | pulled_task = load_balance(this_cpu, this_rq, |
23f0d209 JK |
8346 | sd, CPU_NEWLY_IDLE, |
8347 | &continue_balancing); | |
9bd721c5 JL |
8348 | |
8349 | domain_cost = sched_clock_cpu(this_cpu) - t0; | |
8350 | if (domain_cost > sd->max_newidle_lb_cost) | |
8351 | sd->max_newidle_lb_cost = domain_cost; | |
8352 | ||
8353 | curr_cost += domain_cost; | |
f492e12e | 8354 | } |
1e3c88bd | 8355 | |
31851a98 | 8356 | update_next_balance(sd, &next_balance); |
39a4d9ca JL |
8357 | |
8358 | /* | |
8359 | * Stop searching for tasks to pull if there are | |
8360 | * now runnable tasks on this rq. | |
8361 | */ | |
8362 | if (pulled_task || this_rq->nr_running > 0) | |
1e3c88bd | 8363 | break; |
1e3c88bd | 8364 | } |
dce840a0 | 8365 | rcu_read_unlock(); |
f492e12e PZ |
8366 | |
8367 | raw_spin_lock(&this_rq->lock); | |
8368 | ||
0e5b5337 JL |
8369 | if (curr_cost > this_rq->max_idle_balance_cost) |
8370 | this_rq->max_idle_balance_cost = curr_cost; | |
8371 | ||
e5fc6611 | 8372 | /* |
0e5b5337 JL |
8373 | * While browsing the domains, we released the rq lock, a task could |
8374 | * have been enqueued in the meantime. Since we're not going idle, | |
8375 | * pretend we pulled a task. | |
e5fc6611 | 8376 | */ |
0e5b5337 | 8377 | if (this_rq->cfs.h_nr_running && !pulled_task) |
6e83125c | 8378 | pulled_task = 1; |
e5fc6611 | 8379 | |
52a08ef1 JL |
8380 | out: |
8381 | /* Move the next balance forward */ | |
8382 | if (time_after(this_rq->next_balance, next_balance)) | |
1e3c88bd | 8383 | this_rq->next_balance = next_balance; |
9bd721c5 | 8384 | |
e4aa358b | 8385 | /* Is there a task of a high priority class? */ |
46383648 | 8386 | if (this_rq->nr_running != this_rq->cfs.h_nr_running) |
e4aa358b KT |
8387 | pulled_task = -1; |
8388 | ||
38c6ade2 | 8389 | if (pulled_task) |
6e83125c PZ |
8390 | this_rq->idle_stamp = 0; |
8391 | ||
46f69fa3 MF |
8392 | rq_repin_lock(this_rq, rf); |
8393 | ||
3c4017c1 | 8394 | return pulled_task; |
1e3c88bd PZ |
8395 | } |
8396 | ||
8397 | /* | |
969c7921 TH |
8398 | * active_load_balance_cpu_stop is run by cpu stopper. It pushes |
8399 | * running tasks off the busiest CPU onto idle CPUs. It requires at | |
8400 | * least 1 task to be running on each physical CPU where possible, and | |
8401 | * avoids physical / logical imbalances. | |
1e3c88bd | 8402 | */ |
969c7921 | 8403 | static int active_load_balance_cpu_stop(void *data) |
1e3c88bd | 8404 | { |
969c7921 TH |
8405 | struct rq *busiest_rq = data; |
8406 | int busiest_cpu = cpu_of(busiest_rq); | |
1e3c88bd | 8407 | int target_cpu = busiest_rq->push_cpu; |
969c7921 | 8408 | struct rq *target_rq = cpu_rq(target_cpu); |
1e3c88bd | 8409 | struct sched_domain *sd; |
e5673f28 | 8410 | struct task_struct *p = NULL; |
969c7921 TH |
8411 | |
8412 | raw_spin_lock_irq(&busiest_rq->lock); | |
8413 | ||
8414 | /* make sure the requested cpu hasn't gone down in the meantime */ | |
8415 | if (unlikely(busiest_cpu != smp_processor_id() || | |
8416 | !busiest_rq->active_balance)) | |
8417 | goto out_unlock; | |
1e3c88bd PZ |
8418 | |
8419 | /* Is there any task to move? */ | |
8420 | if (busiest_rq->nr_running <= 1) | |
969c7921 | 8421 | goto out_unlock; |
1e3c88bd PZ |
8422 | |
8423 | /* | |
8424 | * This condition is "impossible", if it occurs | |
8425 | * we need to fix it. Originally reported by | |
8426 | * Bjorn Helgaas on a 128-cpu setup. | |
8427 | */ | |
8428 | BUG_ON(busiest_rq == target_rq); | |
8429 | ||
1e3c88bd | 8430 | /* Search for an sd spanning us and the target CPU. */ |
dce840a0 | 8431 | rcu_read_lock(); |
1e3c88bd PZ |
8432 | for_each_domain(target_cpu, sd) { |
8433 | if ((sd->flags & SD_LOAD_BALANCE) && | |
8434 | cpumask_test_cpu(busiest_cpu, sched_domain_span(sd))) | |
8435 | break; | |
8436 | } | |
8437 | ||
8438 | if (likely(sd)) { | |
8e45cb54 PZ |
8439 | struct lb_env env = { |
8440 | .sd = sd, | |
ddcdf6e7 PZ |
8441 | .dst_cpu = target_cpu, |
8442 | .dst_rq = target_rq, | |
8443 | .src_cpu = busiest_rq->cpu, | |
8444 | .src_rq = busiest_rq, | |
8e45cb54 PZ |
8445 | .idle = CPU_IDLE, |
8446 | }; | |
8447 | ||
ae92882e | 8448 | schedstat_inc(sd->alb_count); |
1e3c88bd | 8449 | |
e5673f28 | 8450 | p = detach_one_task(&env); |
d02c0711 | 8451 | if (p) { |
ae92882e | 8452 | schedstat_inc(sd->alb_pushed); |
d02c0711 SD |
8453 | /* Active balancing done, reset the failure counter. */ |
8454 | sd->nr_balance_failed = 0; | |
8455 | } else { | |
ae92882e | 8456 | schedstat_inc(sd->alb_failed); |
d02c0711 | 8457 | } |
1e3c88bd | 8458 | } |
dce840a0 | 8459 | rcu_read_unlock(); |
969c7921 TH |
8460 | out_unlock: |
8461 | busiest_rq->active_balance = 0; | |
e5673f28 KT |
8462 | raw_spin_unlock(&busiest_rq->lock); |
8463 | ||
8464 | if (p) | |
8465 | attach_one_task(target_rq, p); | |
8466 | ||
8467 | local_irq_enable(); | |
8468 | ||
969c7921 | 8469 | return 0; |
1e3c88bd PZ |
8470 | } |
8471 | ||
d987fc7f MG |
8472 | static inline int on_null_domain(struct rq *rq) |
8473 | { | |
8474 | return unlikely(!rcu_dereference_sched(rq->sd)); | |
8475 | } | |
8476 | ||
3451d024 | 8477 | #ifdef CONFIG_NO_HZ_COMMON |
83cd4fe2 VP |
8478 | /* |
8479 | * idle load balancing details | |
83cd4fe2 VP |
8480 | * - When one of the busy CPUs notice that there may be an idle rebalancing |
8481 | * needed, they will kick the idle load balancer, which then does idle | |
8482 | * load balancing for all the idle CPUs. | |
8483 | */ | |
1e3c88bd | 8484 | static struct { |
83cd4fe2 | 8485 | cpumask_var_t idle_cpus_mask; |
0b005cf5 | 8486 | atomic_t nr_cpus; |
83cd4fe2 VP |
8487 | unsigned long next_balance; /* in jiffy units */ |
8488 | } nohz ____cacheline_aligned; | |
1e3c88bd | 8489 | |
3dd0337d | 8490 | static inline int find_new_ilb(void) |
1e3c88bd | 8491 | { |
0b005cf5 | 8492 | int ilb = cpumask_first(nohz.idle_cpus_mask); |
1e3c88bd | 8493 | |
786d6dc7 SS |
8494 | if (ilb < nr_cpu_ids && idle_cpu(ilb)) |
8495 | return ilb; | |
8496 | ||
8497 | return nr_cpu_ids; | |
1e3c88bd | 8498 | } |
1e3c88bd | 8499 | |
83cd4fe2 VP |
8500 | /* |
8501 | * Kick a CPU to do the nohz balancing, if it is time for it. We pick the | |
8502 | * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle | |
8503 | * CPU (if there is one). | |
8504 | */ | |
0aeeeeba | 8505 | static void nohz_balancer_kick(void) |
83cd4fe2 VP |
8506 | { |
8507 | int ilb_cpu; | |
8508 | ||
8509 | nohz.next_balance++; | |
8510 | ||
3dd0337d | 8511 | ilb_cpu = find_new_ilb(); |
83cd4fe2 | 8512 | |
0b005cf5 SS |
8513 | if (ilb_cpu >= nr_cpu_ids) |
8514 | return; | |
83cd4fe2 | 8515 | |
cd490c5b | 8516 | if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu))) |
1c792db7 SS |
8517 | return; |
8518 | /* | |
8519 | * Use smp_send_reschedule() instead of resched_cpu(). | |
8520 | * This way we generate a sched IPI on the target cpu which | |
8521 | * is idle. And the softirq performing nohz idle load balance | |
8522 | * will be run before returning from the IPI. | |
8523 | */ | |
8524 | smp_send_reschedule(ilb_cpu); | |
83cd4fe2 VP |
8525 | return; |
8526 | } | |
8527 | ||
20a5c8cc | 8528 | void nohz_balance_exit_idle(unsigned int cpu) |
71325960 SS |
8529 | { |
8530 | if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) { | |
d987fc7f MG |
8531 | /* |
8532 | * Completely isolated CPUs don't ever set, so we must test. | |
8533 | */ | |
8534 | if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) { | |
8535 | cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); | |
8536 | atomic_dec(&nohz.nr_cpus); | |
8537 | } | |
71325960 SS |
8538 | clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); |
8539 | } | |
8540 | } | |
8541 | ||
69e1e811 SS |
8542 | static inline void set_cpu_sd_state_busy(void) |
8543 | { | |
8544 | struct sched_domain *sd; | |
37dc6b50 | 8545 | int cpu = smp_processor_id(); |
69e1e811 | 8546 | |
69e1e811 | 8547 | rcu_read_lock(); |
0e369d75 | 8548 | sd = rcu_dereference(per_cpu(sd_llc, cpu)); |
25f55d9d VG |
8549 | |
8550 | if (!sd || !sd->nohz_idle) | |
8551 | goto unlock; | |
8552 | sd->nohz_idle = 0; | |
8553 | ||
0e369d75 | 8554 | atomic_inc(&sd->shared->nr_busy_cpus); |
25f55d9d | 8555 | unlock: |
69e1e811 SS |
8556 | rcu_read_unlock(); |
8557 | } | |
8558 | ||
8559 | void set_cpu_sd_state_idle(void) | |
8560 | { | |
8561 | struct sched_domain *sd; | |
37dc6b50 | 8562 | int cpu = smp_processor_id(); |
69e1e811 | 8563 | |
69e1e811 | 8564 | rcu_read_lock(); |
0e369d75 | 8565 | sd = rcu_dereference(per_cpu(sd_llc, cpu)); |
25f55d9d VG |
8566 | |
8567 | if (!sd || sd->nohz_idle) | |
8568 | goto unlock; | |
8569 | sd->nohz_idle = 1; | |
8570 | ||
0e369d75 | 8571 | atomic_dec(&sd->shared->nr_busy_cpus); |
25f55d9d | 8572 | unlock: |
69e1e811 SS |
8573 | rcu_read_unlock(); |
8574 | } | |
8575 | ||
1e3c88bd | 8576 | /* |
c1cc017c | 8577 | * This routine will record that the cpu is going idle with tick stopped. |
0b005cf5 | 8578 | * This info will be used in performing idle load balancing in the future. |
1e3c88bd | 8579 | */ |
c1cc017c | 8580 | void nohz_balance_enter_idle(int cpu) |
1e3c88bd | 8581 | { |
71325960 SS |
8582 | /* |
8583 | * If this cpu is going down, then nothing needs to be done. | |
8584 | */ | |
8585 | if (!cpu_active(cpu)) | |
8586 | return; | |
8587 | ||
c1cc017c AS |
8588 | if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) |
8589 | return; | |
1e3c88bd | 8590 | |
d987fc7f MG |
8591 | /* |
8592 | * If we're a completely isolated CPU, we don't play. | |
8593 | */ | |
8594 | if (on_null_domain(cpu_rq(cpu))) | |
8595 | return; | |
8596 | ||
c1cc017c AS |
8597 | cpumask_set_cpu(cpu, nohz.idle_cpus_mask); |
8598 | atomic_inc(&nohz.nr_cpus); | |
8599 | set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); | |
1e3c88bd PZ |
8600 | } |
8601 | #endif | |
8602 | ||
8603 | static DEFINE_SPINLOCK(balancing); | |
8604 | ||
49c022e6 PZ |
8605 | /* |
8606 | * Scale the max load_balance interval with the number of CPUs in the system. | |
8607 | * This trades load-balance latency on larger machines for less cross talk. | |
8608 | */ | |
029632fb | 8609 | void update_max_interval(void) |
49c022e6 PZ |
8610 | { |
8611 | max_load_balance_interval = HZ*num_online_cpus()/10; | |
8612 | } | |
8613 | ||
1e3c88bd PZ |
8614 | /* |
8615 | * It checks each scheduling domain to see if it is due to be balanced, | |
8616 | * and initiates a balancing operation if so. | |
8617 | * | |
b9b0853a | 8618 | * Balancing parameters are set up in init_sched_domains. |
1e3c88bd | 8619 | */ |
f7ed0a89 | 8620 | static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) |
1e3c88bd | 8621 | { |
23f0d209 | 8622 | int continue_balancing = 1; |
f7ed0a89 | 8623 | int cpu = rq->cpu; |
1e3c88bd | 8624 | unsigned long interval; |
04f733b4 | 8625 | struct sched_domain *sd; |
1e3c88bd PZ |
8626 | /* Earliest time when we have to do rebalance again */ |
8627 | unsigned long next_balance = jiffies + 60*HZ; | |
8628 | int update_next_balance = 0; | |
f48627e6 JL |
8629 | int need_serialize, need_decay = 0; |
8630 | u64 max_cost = 0; | |
1e3c88bd | 8631 | |
48a16753 | 8632 | update_blocked_averages(cpu); |
2069dd75 | 8633 | |
dce840a0 | 8634 | rcu_read_lock(); |
1e3c88bd | 8635 | for_each_domain(cpu, sd) { |
f48627e6 JL |
8636 | /* |
8637 | * Decay the newidle max times here because this is a regular | |
8638 | * visit to all the domains. Decay ~1% per second. | |
8639 | */ | |
8640 | if (time_after(jiffies, sd->next_decay_max_lb_cost)) { | |
8641 | sd->max_newidle_lb_cost = | |
8642 | (sd->max_newidle_lb_cost * 253) / 256; | |
8643 | sd->next_decay_max_lb_cost = jiffies + HZ; | |
8644 | need_decay = 1; | |
8645 | } | |
8646 | max_cost += sd->max_newidle_lb_cost; | |
8647 | ||
1e3c88bd PZ |
8648 | if (!(sd->flags & SD_LOAD_BALANCE)) |
8649 | continue; | |
8650 | ||
f48627e6 JL |
8651 | /* |
8652 | * Stop the load balance at this level. There is another | |
8653 | * CPU in our sched group which is doing load balancing more | |
8654 | * actively. | |
8655 | */ | |
8656 | if (!continue_balancing) { | |
8657 | if (need_decay) | |
8658 | continue; | |
8659 | break; | |
8660 | } | |
8661 | ||
52a08ef1 | 8662 | interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
1e3c88bd PZ |
8663 | |
8664 | need_serialize = sd->flags & SD_SERIALIZE; | |
1e3c88bd PZ |
8665 | if (need_serialize) { |
8666 | if (!spin_trylock(&balancing)) | |
8667 | goto out; | |
8668 | } | |
8669 | ||
8670 | if (time_after_eq(jiffies, sd->last_balance + interval)) { | |
23f0d209 | 8671 | if (load_balance(cpu, rq, sd, idle, &continue_balancing)) { |
1e3c88bd | 8672 | /* |
6263322c | 8673 | * The LBF_DST_PINNED logic could have changed |
de5eb2dd JK |
8674 | * env->dst_cpu, so we can't know our idle |
8675 | * state even if we migrated tasks. Update it. | |
1e3c88bd | 8676 | */ |
de5eb2dd | 8677 | idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE; |
1e3c88bd PZ |
8678 | } |
8679 | sd->last_balance = jiffies; | |
52a08ef1 | 8680 | interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
1e3c88bd PZ |
8681 | } |
8682 | if (need_serialize) | |
8683 | spin_unlock(&balancing); | |
8684 | out: | |
8685 | if (time_after(next_balance, sd->last_balance + interval)) { | |
8686 | next_balance = sd->last_balance + interval; | |
8687 | update_next_balance = 1; | |
8688 | } | |
f48627e6 JL |
8689 | } |
8690 | if (need_decay) { | |
1e3c88bd | 8691 | /* |
f48627e6 JL |
8692 | * Ensure the rq-wide value also decays but keep it at a |
8693 | * reasonable floor to avoid funnies with rq->avg_idle. | |
1e3c88bd | 8694 | */ |
f48627e6 JL |
8695 | rq->max_idle_balance_cost = |
8696 | max((u64)sysctl_sched_migration_cost, max_cost); | |
1e3c88bd | 8697 | } |
dce840a0 | 8698 | rcu_read_unlock(); |
1e3c88bd PZ |
8699 | |
8700 | /* | |
8701 | * next_balance will be updated only when there is a need. | |
8702 | * When the cpu is attached to null domain for ex, it will not be | |
8703 | * updated. | |
8704 | */ | |
c5afb6a8 | 8705 | if (likely(update_next_balance)) { |
1e3c88bd | 8706 | rq->next_balance = next_balance; |
c5afb6a8 VG |
8707 | |
8708 | #ifdef CONFIG_NO_HZ_COMMON | |
8709 | /* | |
8710 | * If this CPU has been elected to perform the nohz idle | |
8711 | * balance. Other idle CPUs have already rebalanced with | |
8712 | * nohz_idle_balance() and nohz.next_balance has been | |
8713 | * updated accordingly. This CPU is now running the idle load | |
8714 | * balance for itself and we need to update the | |
8715 | * nohz.next_balance accordingly. | |
8716 | */ | |
8717 | if ((idle == CPU_IDLE) && time_after(nohz.next_balance, rq->next_balance)) | |
8718 | nohz.next_balance = rq->next_balance; | |
8719 | #endif | |
8720 | } | |
1e3c88bd PZ |
8721 | } |
8722 | ||
3451d024 | 8723 | #ifdef CONFIG_NO_HZ_COMMON |
1e3c88bd | 8724 | /* |
3451d024 | 8725 | * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the |
1e3c88bd PZ |
8726 | * rebalancing for all the cpus for whom scheduler ticks are stopped. |
8727 | */ | |
208cb16b | 8728 | static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) |
83cd4fe2 | 8729 | { |
208cb16b | 8730 | int this_cpu = this_rq->cpu; |
83cd4fe2 VP |
8731 | struct rq *rq; |
8732 | int balance_cpu; | |
c5afb6a8 VG |
8733 | /* Earliest time when we have to do rebalance again */ |
8734 | unsigned long next_balance = jiffies + 60*HZ; | |
8735 | int update_next_balance = 0; | |
83cd4fe2 | 8736 | |
1c792db7 SS |
8737 | if (idle != CPU_IDLE || |
8738 | !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu))) | |
8739 | goto end; | |
83cd4fe2 VP |
8740 | |
8741 | for_each_cpu(balance_cpu, nohz.idle_cpus_mask) { | |
8a6d42d1 | 8742 | if (balance_cpu == this_cpu || !idle_cpu(balance_cpu)) |
83cd4fe2 VP |
8743 | continue; |
8744 | ||
8745 | /* | |
8746 | * If this cpu gets work to do, stop the load balancing | |
8747 | * work being done for other cpus. Next load | |
8748 | * balancing owner will pick it up. | |
8749 | */ | |
1c792db7 | 8750 | if (need_resched()) |
83cd4fe2 | 8751 | break; |
83cd4fe2 | 8752 | |
5ed4f1d9 VG |
8753 | rq = cpu_rq(balance_cpu); |
8754 | ||
ed61bbc6 TC |
8755 | /* |
8756 | * If time for next balance is due, | |
8757 | * do the balance. | |
8758 | */ | |
8759 | if (time_after_eq(jiffies, rq->next_balance)) { | |
8760 | raw_spin_lock_irq(&rq->lock); | |
8761 | update_rq_clock(rq); | |
cee1afce | 8762 | cpu_load_update_idle(rq); |
ed61bbc6 TC |
8763 | raw_spin_unlock_irq(&rq->lock); |
8764 | rebalance_domains(rq, CPU_IDLE); | |
8765 | } | |
83cd4fe2 | 8766 | |
c5afb6a8 VG |
8767 | if (time_after(next_balance, rq->next_balance)) { |
8768 | next_balance = rq->next_balance; | |
8769 | update_next_balance = 1; | |
8770 | } | |
83cd4fe2 | 8771 | } |
c5afb6a8 VG |
8772 | |
8773 | /* | |
8774 | * next_balance will be updated only when there is a need. | |
8775 | * When the CPU is attached to null domain for ex, it will not be | |
8776 | * updated. | |
8777 | */ | |
8778 | if (likely(update_next_balance)) | |
8779 | nohz.next_balance = next_balance; | |
1c792db7 SS |
8780 | end: |
8781 | clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)); | |
83cd4fe2 VP |
8782 | } |
8783 | ||
8784 | /* | |
0b005cf5 | 8785 | * Current heuristic for kicking the idle load balancer in the presence |
1aaf90a4 | 8786 | * of an idle cpu in the system. |
0b005cf5 | 8787 | * - This rq has more than one task. |
1aaf90a4 VG |
8788 | * - This rq has at least one CFS task and the capacity of the CPU is |
8789 | * significantly reduced because of RT tasks or IRQs. | |
8790 | * - At parent of LLC scheduler domain level, this cpu's scheduler group has | |
8791 | * multiple busy cpu. | |
0b005cf5 SS |
8792 | * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler |
8793 | * domain span are idle. | |
83cd4fe2 | 8794 | */ |
1aaf90a4 | 8795 | static inline bool nohz_kick_needed(struct rq *rq) |
83cd4fe2 VP |
8796 | { |
8797 | unsigned long now = jiffies; | |
0e369d75 | 8798 | struct sched_domain_shared *sds; |
0b005cf5 | 8799 | struct sched_domain *sd; |
afe06efd | 8800 | int nr_busy, i, cpu = rq->cpu; |
1aaf90a4 | 8801 | bool kick = false; |
83cd4fe2 | 8802 | |
4a725627 | 8803 | if (unlikely(rq->idle_balance)) |
1aaf90a4 | 8804 | return false; |
83cd4fe2 | 8805 | |
1c792db7 SS |
8806 | /* |
8807 | * We may be recently in ticked or tickless idle mode. At the first | |
8808 | * busy tick after returning from idle, we will update the busy stats. | |
8809 | */ | |
69e1e811 | 8810 | set_cpu_sd_state_busy(); |
c1cc017c | 8811 | nohz_balance_exit_idle(cpu); |
0b005cf5 SS |
8812 | |
8813 | /* | |
8814 | * None are in tickless mode and hence no need for NOHZ idle load | |
8815 | * balancing. | |
8816 | */ | |
8817 | if (likely(!atomic_read(&nohz.nr_cpus))) | |
1aaf90a4 | 8818 | return false; |
1c792db7 SS |
8819 | |
8820 | if (time_before(now, nohz.next_balance)) | |
1aaf90a4 | 8821 | return false; |
83cd4fe2 | 8822 | |
0b005cf5 | 8823 | if (rq->nr_running >= 2) |
1aaf90a4 | 8824 | return true; |
83cd4fe2 | 8825 | |
067491b7 | 8826 | rcu_read_lock(); |
0e369d75 PZ |
8827 | sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); |
8828 | if (sds) { | |
8829 | /* | |
8830 | * XXX: write a coherent comment on why we do this. | |
8831 | * See also: http://lkml.kernel.org/r/20111202010832.602203411@sbsiddha-desk.sc.intel.com | |
8832 | */ | |
8833 | nr_busy = atomic_read(&sds->nr_busy_cpus); | |
1aaf90a4 VG |
8834 | if (nr_busy > 1) { |
8835 | kick = true; | |
8836 | goto unlock; | |
8837 | } | |
8838 | ||
83cd4fe2 | 8839 | } |
37dc6b50 | 8840 | |
1aaf90a4 VG |
8841 | sd = rcu_dereference(rq->sd); |
8842 | if (sd) { | |
8843 | if ((rq->cfs.h_nr_running >= 1) && | |
8844 | check_cpu_capacity(rq, sd)) { | |
8845 | kick = true; | |
8846 | goto unlock; | |
8847 | } | |
8848 | } | |
37dc6b50 | 8849 | |
1aaf90a4 | 8850 | sd = rcu_dereference(per_cpu(sd_asym, cpu)); |
afe06efd TC |
8851 | if (sd) { |
8852 | for_each_cpu(i, sched_domain_span(sd)) { | |
8853 | if (i == cpu || | |
8854 | !cpumask_test_cpu(i, nohz.idle_cpus_mask)) | |
8855 | continue; | |
067491b7 | 8856 | |
afe06efd TC |
8857 | if (sched_asym_prefer(i, cpu)) { |
8858 | kick = true; | |
8859 | goto unlock; | |
8860 | } | |
8861 | } | |
8862 | } | |
1aaf90a4 | 8863 | unlock: |
067491b7 | 8864 | rcu_read_unlock(); |
1aaf90a4 | 8865 | return kick; |
83cd4fe2 VP |
8866 | } |
8867 | #else | |
208cb16b | 8868 | static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { } |
83cd4fe2 VP |
8869 | #endif |
8870 | ||
8871 | /* | |
8872 | * run_rebalance_domains is triggered when needed from the scheduler tick. | |
8873 | * Also triggered for nohz idle balancing (with nohz_balancing_kick set). | |
8874 | */ | |
0766f788 | 8875 | static __latent_entropy void run_rebalance_domains(struct softirq_action *h) |
1e3c88bd | 8876 | { |
208cb16b | 8877 | struct rq *this_rq = this_rq(); |
6eb57e0d | 8878 | enum cpu_idle_type idle = this_rq->idle_balance ? |
1e3c88bd PZ |
8879 | CPU_IDLE : CPU_NOT_IDLE; |
8880 | ||
1e3c88bd | 8881 | /* |
83cd4fe2 | 8882 | * If this cpu has a pending nohz_balance_kick, then do the |
1e3c88bd | 8883 | * balancing on behalf of the other idle cpus whose ticks are |
d4573c3e PM |
8884 | * stopped. Do nohz_idle_balance *before* rebalance_domains to |
8885 | * give the idle cpus a chance to load balance. Else we may | |
8886 | * load balance only within the local sched_domain hierarchy | |
8887 | * and abort nohz_idle_balance altogether if we pull some load. | |
1e3c88bd | 8888 | */ |
208cb16b | 8889 | nohz_idle_balance(this_rq, idle); |
d4573c3e | 8890 | rebalance_domains(this_rq, idle); |
1e3c88bd PZ |
8891 | } |
8892 | ||
1e3c88bd PZ |
8893 | /* |
8894 | * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing. | |
1e3c88bd | 8895 | */ |
7caff66f | 8896 | void trigger_load_balance(struct rq *rq) |
1e3c88bd | 8897 | { |
1e3c88bd | 8898 | /* Don't need to rebalance while attached to NULL domain */ |
c726099e DL |
8899 | if (unlikely(on_null_domain(rq))) |
8900 | return; | |
8901 | ||
8902 | if (time_after_eq(jiffies, rq->next_balance)) | |
1e3c88bd | 8903 | raise_softirq(SCHED_SOFTIRQ); |
3451d024 | 8904 | #ifdef CONFIG_NO_HZ_COMMON |
c726099e | 8905 | if (nohz_kick_needed(rq)) |
0aeeeeba | 8906 | nohz_balancer_kick(); |
83cd4fe2 | 8907 | #endif |
1e3c88bd PZ |
8908 | } |
8909 | ||
0bcdcf28 CE |
8910 | static void rq_online_fair(struct rq *rq) |
8911 | { | |
8912 | update_sysctl(); | |
0e59bdae KT |
8913 | |
8914 | update_runtime_enabled(rq); | |
0bcdcf28 CE |
8915 | } |
8916 | ||
8917 | static void rq_offline_fair(struct rq *rq) | |
8918 | { | |
8919 | update_sysctl(); | |
a4c96ae3 PB |
8920 | |
8921 | /* Ensure any throttled groups are reachable by pick_next_task */ | |
8922 | unthrottle_offline_cfs_rqs(rq); | |
0bcdcf28 CE |
8923 | } |
8924 | ||
55e12e5e | 8925 | #endif /* CONFIG_SMP */ |
e1d1484f | 8926 | |
bf0f6f24 IM |
8927 | /* |
8928 | * scheduler tick hitting a task of our scheduling class: | |
8929 | */ | |
8f4d37ec | 8930 | static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) |
bf0f6f24 IM |
8931 | { |
8932 | struct cfs_rq *cfs_rq; | |
8933 | struct sched_entity *se = &curr->se; | |
8934 | ||
8935 | for_each_sched_entity(se) { | |
8936 | cfs_rq = cfs_rq_of(se); | |
8f4d37ec | 8937 | entity_tick(cfs_rq, se, queued); |
bf0f6f24 | 8938 | } |
18bf2805 | 8939 | |
b52da86e | 8940 | if (static_branch_unlikely(&sched_numa_balancing)) |
cbee9f88 | 8941 | task_tick_numa(rq, curr); |
bf0f6f24 IM |
8942 | } |
8943 | ||
8944 | /* | |
cd29fe6f PZ |
8945 | * called on fork with the child task as argument from the parent's context |
8946 | * - child not yet on the tasklist | |
8947 | * - preemption disabled | |
bf0f6f24 | 8948 | */ |
cd29fe6f | 8949 | static void task_fork_fair(struct task_struct *p) |
bf0f6f24 | 8950 | { |
4fc420c9 DN |
8951 | struct cfs_rq *cfs_rq; |
8952 | struct sched_entity *se = &p->se, *curr; | |
cd29fe6f | 8953 | struct rq *rq = this_rq(); |
bf0f6f24 | 8954 | |
e210bffd | 8955 | raw_spin_lock(&rq->lock); |
861d034e PZ |
8956 | update_rq_clock(rq); |
8957 | ||
4fc420c9 DN |
8958 | cfs_rq = task_cfs_rq(current); |
8959 | curr = cfs_rq->curr; | |
e210bffd PZ |
8960 | if (curr) { |
8961 | update_curr(cfs_rq); | |
b5d9d734 | 8962 | se->vruntime = curr->vruntime; |
e210bffd | 8963 | } |
aeb73b04 | 8964 | place_entity(cfs_rq, se, 1); |
4d78e7b6 | 8965 | |
cd29fe6f | 8966 | if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { |
87fefa38 | 8967 | /* |
edcb60a3 IM |
8968 | * Upon rescheduling, sched_class::put_prev_task() will place |
8969 | * 'current' within the tree based on its new key value. | |
8970 | */ | |
4d78e7b6 | 8971 | swap(curr->vruntime, se->vruntime); |
8875125e | 8972 | resched_curr(rq); |
4d78e7b6 | 8973 | } |
bf0f6f24 | 8974 | |
88ec22d3 | 8975 | se->vruntime -= cfs_rq->min_vruntime; |
e210bffd | 8976 | raw_spin_unlock(&rq->lock); |
bf0f6f24 IM |
8977 | } |
8978 | ||
cb469845 SR |
8979 | /* |
8980 | * Priority of the task has changed. Check to see if we preempt | |
8981 | * the current task. | |
8982 | */ | |
da7a735e PZ |
8983 | static void |
8984 | prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio) | |
cb469845 | 8985 | { |
da0c1e65 | 8986 | if (!task_on_rq_queued(p)) |
da7a735e PZ |
8987 | return; |
8988 | ||
cb469845 SR |
8989 | /* |
8990 | * Reschedule if we are currently running on this runqueue and | |
8991 | * our priority decreased, or if we are not currently running on | |
8992 | * this runqueue and our priority is higher than the current's | |
8993 | */ | |
da7a735e | 8994 | if (rq->curr == p) { |
cb469845 | 8995 | if (p->prio > oldprio) |
8875125e | 8996 | resched_curr(rq); |
cb469845 | 8997 | } else |
15afe09b | 8998 | check_preempt_curr(rq, p, 0); |
cb469845 SR |
8999 | } |
9000 | ||
daa59407 | 9001 | static inline bool vruntime_normalized(struct task_struct *p) |
da7a735e PZ |
9002 | { |
9003 | struct sched_entity *se = &p->se; | |
da7a735e PZ |
9004 | |
9005 | /* | |
daa59407 BP |
9006 | * In both the TASK_ON_RQ_QUEUED and TASK_ON_RQ_MIGRATING cases, |
9007 | * the dequeue_entity(.flags=0) will already have normalized the | |
9008 | * vruntime. | |
9009 | */ | |
9010 | if (p->on_rq) | |
9011 | return true; | |
9012 | ||
9013 | /* | |
9014 | * When !on_rq, vruntime of the task has usually NOT been normalized. | |
9015 | * But there are some cases where it has already been normalized: | |
da7a735e | 9016 | * |
daa59407 BP |
9017 | * - A forked child which is waiting for being woken up by |
9018 | * wake_up_new_task(). | |
9019 | * - A task which has been woken up by try_to_wake_up() and | |
9020 | * waiting for actually being woken up by sched_ttwu_pending(). | |
da7a735e | 9021 | */ |
daa59407 BP |
9022 | if (!se->sum_exec_runtime || p->state == TASK_WAKING) |
9023 | return true; | |
9024 | ||
9025 | return false; | |
9026 | } | |
9027 | ||
09a43ace VG |
9028 | #ifdef CONFIG_FAIR_GROUP_SCHED |
9029 | /* | |
9030 | * Propagate the changes of the sched_entity across the tg tree to make it | |
9031 | * visible to the root | |
9032 | */ | |
9033 | static void propagate_entity_cfs_rq(struct sched_entity *se) | |
9034 | { | |
9035 | struct cfs_rq *cfs_rq; | |
9036 | ||
9037 | /* Start to propagate at parent */ | |
9038 | se = se->parent; | |
9039 | ||
9040 | for_each_sched_entity(se) { | |
9041 | cfs_rq = cfs_rq_of(se); | |
9042 | ||
9043 | if (cfs_rq_throttled(cfs_rq)) | |
9044 | break; | |
9045 | ||
9046 | update_load_avg(se, UPDATE_TG); | |
9047 | } | |
9048 | } | |
9049 | #else | |
9050 | static void propagate_entity_cfs_rq(struct sched_entity *se) { } | |
9051 | #endif | |
9052 | ||
df217913 | 9053 | static void detach_entity_cfs_rq(struct sched_entity *se) |
daa59407 | 9054 | { |
daa59407 BP |
9055 | struct cfs_rq *cfs_rq = cfs_rq_of(se); |
9056 | ||
9d89c257 | 9057 | /* Catch up with the cfs_rq and remove our load when we leave */ |
d31b1a66 | 9058 | update_load_avg(se, 0); |
a05e8c51 | 9059 | detach_entity_load_avg(cfs_rq, se); |
7c3edd2c | 9060 | update_tg_load_avg(cfs_rq, false); |
09a43ace | 9061 | propagate_entity_cfs_rq(se); |
da7a735e PZ |
9062 | } |
9063 | ||
df217913 | 9064 | static void attach_entity_cfs_rq(struct sched_entity *se) |
cb469845 | 9065 | { |
daa59407 | 9066 | struct cfs_rq *cfs_rq = cfs_rq_of(se); |
7855a35a BP |
9067 | |
9068 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
eb7a59b2 M |
9069 | /* |
9070 | * Since the real-depth could have been changed (only FAIR | |
9071 | * class maintain depth value), reset depth properly. | |
9072 | */ | |
9073 | se->depth = se->parent ? se->parent->depth + 1 : 0; | |
9074 | #endif | |
7855a35a | 9075 | |
df217913 | 9076 | /* Synchronize entity with its cfs_rq */ |
d31b1a66 | 9077 | update_load_avg(se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD); |
daa59407 | 9078 | attach_entity_load_avg(cfs_rq, se); |
7c3edd2c | 9079 | update_tg_load_avg(cfs_rq, false); |
09a43ace | 9080 | propagate_entity_cfs_rq(se); |
df217913 VG |
9081 | } |
9082 | ||
9083 | static void detach_task_cfs_rq(struct task_struct *p) | |
9084 | { | |
9085 | struct sched_entity *se = &p->se; | |
9086 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
9087 | ||
9088 | if (!vruntime_normalized(p)) { | |
9089 | /* | |
9090 | * Fix up our vruntime so that the current sleep doesn't | |
9091 | * cause 'unlimited' sleep bonus. | |
9092 | */ | |
9093 | place_entity(cfs_rq, se, 0); | |
9094 | se->vruntime -= cfs_rq->min_vruntime; | |
9095 | } | |
9096 | ||
9097 | detach_entity_cfs_rq(se); | |
9098 | } | |
9099 | ||
9100 | static void attach_task_cfs_rq(struct task_struct *p) | |
9101 | { | |
9102 | struct sched_entity *se = &p->se; | |
9103 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
9104 | ||
9105 | attach_entity_cfs_rq(se); | |
daa59407 BP |
9106 | |
9107 | if (!vruntime_normalized(p)) | |
9108 | se->vruntime += cfs_rq->min_vruntime; | |
9109 | } | |
6efdb105 | 9110 | |
daa59407 BP |
9111 | static void switched_from_fair(struct rq *rq, struct task_struct *p) |
9112 | { | |
9113 | detach_task_cfs_rq(p); | |
9114 | } | |
9115 | ||
9116 | static void switched_to_fair(struct rq *rq, struct task_struct *p) | |
9117 | { | |
9118 | attach_task_cfs_rq(p); | |
7855a35a | 9119 | |
daa59407 | 9120 | if (task_on_rq_queued(p)) { |
7855a35a | 9121 | /* |
daa59407 BP |
9122 | * We were most likely switched from sched_rt, so |
9123 | * kick off the schedule if running, otherwise just see | |
9124 | * if we can still preempt the current task. | |
7855a35a | 9125 | */ |
daa59407 BP |
9126 | if (rq->curr == p) |
9127 | resched_curr(rq); | |
9128 | else | |
9129 | check_preempt_curr(rq, p, 0); | |
7855a35a | 9130 | } |
cb469845 SR |
9131 | } |
9132 | ||
83b699ed SV |
9133 | /* Account for a task changing its policy or group. |
9134 | * | |
9135 | * This routine is mostly called to set cfs_rq->curr field when a task | |
9136 | * migrates between groups/classes. | |
9137 | */ | |
9138 | static void set_curr_task_fair(struct rq *rq) | |
9139 | { | |
9140 | struct sched_entity *se = &rq->curr->se; | |
9141 | ||
ec12cb7f PT |
9142 | for_each_sched_entity(se) { |
9143 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
9144 | ||
9145 | set_next_entity(cfs_rq, se); | |
9146 | /* ensure bandwidth has been allocated on our new cfs_rq */ | |
9147 | account_cfs_rq_runtime(cfs_rq, 0); | |
9148 | } | |
83b699ed SV |
9149 | } |
9150 | ||
029632fb PZ |
9151 | void init_cfs_rq(struct cfs_rq *cfs_rq) |
9152 | { | |
9153 | cfs_rq->tasks_timeline = RB_ROOT; | |
029632fb PZ |
9154 | cfs_rq->min_vruntime = (u64)(-(1LL << 20)); |
9155 | #ifndef CONFIG_64BIT | |
9156 | cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; | |
9157 | #endif | |
141965c7 | 9158 | #ifdef CONFIG_SMP |
09a43ace VG |
9159 | #ifdef CONFIG_FAIR_GROUP_SCHED |
9160 | cfs_rq->propagate_avg = 0; | |
9161 | #endif | |
9d89c257 YD |
9162 | atomic_long_set(&cfs_rq->removed_load_avg, 0); |
9163 | atomic_long_set(&cfs_rq->removed_util_avg, 0); | |
9ee474f5 | 9164 | #endif |
029632fb PZ |
9165 | } |
9166 | ||
810b3817 | 9167 | #ifdef CONFIG_FAIR_GROUP_SCHED |
ea86cb4b VG |
9168 | static void task_set_group_fair(struct task_struct *p) |
9169 | { | |
9170 | struct sched_entity *se = &p->se; | |
9171 | ||
9172 | set_task_rq(p, task_cpu(p)); | |
9173 | se->depth = se->parent ? se->parent->depth + 1 : 0; | |
9174 | } | |
9175 | ||
bc54da21 | 9176 | static void task_move_group_fair(struct task_struct *p) |
810b3817 | 9177 | { |
daa59407 | 9178 | detach_task_cfs_rq(p); |
b2b5ce02 | 9179 | set_task_rq(p, task_cpu(p)); |
6efdb105 BP |
9180 | |
9181 | #ifdef CONFIG_SMP | |
9182 | /* Tell se's cfs_rq has been changed -- migrated */ | |
9183 | p->se.avg.last_update_time = 0; | |
9184 | #endif | |
daa59407 | 9185 | attach_task_cfs_rq(p); |
810b3817 | 9186 | } |
029632fb | 9187 | |
ea86cb4b VG |
9188 | static void task_change_group_fair(struct task_struct *p, int type) |
9189 | { | |
9190 | switch (type) { | |
9191 | case TASK_SET_GROUP: | |
9192 | task_set_group_fair(p); | |
9193 | break; | |
9194 | ||
9195 | case TASK_MOVE_GROUP: | |
9196 | task_move_group_fair(p); | |
9197 | break; | |
9198 | } | |
9199 | } | |
9200 | ||
029632fb PZ |
9201 | void free_fair_sched_group(struct task_group *tg) |
9202 | { | |
9203 | int i; | |
9204 | ||
9205 | destroy_cfs_bandwidth(tg_cfs_bandwidth(tg)); | |
9206 | ||
9207 | for_each_possible_cpu(i) { | |
9208 | if (tg->cfs_rq) | |
9209 | kfree(tg->cfs_rq[i]); | |
6fe1f348 | 9210 | if (tg->se) |
029632fb PZ |
9211 | kfree(tg->se[i]); |
9212 | } | |
9213 | ||
9214 | kfree(tg->cfs_rq); | |
9215 | kfree(tg->se); | |
9216 | } | |
9217 | ||
9218 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) | |
9219 | { | |
029632fb | 9220 | struct sched_entity *se; |
b7fa30c9 | 9221 | struct cfs_rq *cfs_rq; |
029632fb PZ |
9222 | int i; |
9223 | ||
9224 | tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL); | |
9225 | if (!tg->cfs_rq) | |
9226 | goto err; | |
9227 | tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL); | |
9228 | if (!tg->se) | |
9229 | goto err; | |
9230 | ||
9231 | tg->shares = NICE_0_LOAD; | |
9232 | ||
9233 | init_cfs_bandwidth(tg_cfs_bandwidth(tg)); | |
9234 | ||
9235 | for_each_possible_cpu(i) { | |
9236 | cfs_rq = kzalloc_node(sizeof(struct cfs_rq), | |
9237 | GFP_KERNEL, cpu_to_node(i)); | |
9238 | if (!cfs_rq) | |
9239 | goto err; | |
9240 | ||
9241 | se = kzalloc_node(sizeof(struct sched_entity), | |
9242 | GFP_KERNEL, cpu_to_node(i)); | |
9243 | if (!se) | |
9244 | goto err_free_rq; | |
9245 | ||
9246 | init_cfs_rq(cfs_rq); | |
9247 | init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]); | |
540247fb | 9248 | init_entity_runnable_average(se); |
029632fb PZ |
9249 | } |
9250 | ||
9251 | return 1; | |
9252 | ||
9253 | err_free_rq: | |
9254 | kfree(cfs_rq); | |
9255 | err: | |
9256 | return 0; | |
9257 | } | |
9258 | ||
8663e24d PZ |
9259 | void online_fair_sched_group(struct task_group *tg) |
9260 | { | |
9261 | struct sched_entity *se; | |
9262 | struct rq *rq; | |
9263 | int i; | |
9264 | ||
9265 | for_each_possible_cpu(i) { | |
9266 | rq = cpu_rq(i); | |
9267 | se = tg->se[i]; | |
9268 | ||
9269 | raw_spin_lock_irq(&rq->lock); | |
d0326691 | 9270 | attach_entity_cfs_rq(se); |
55e16d30 | 9271 | sync_throttle(tg, i); |
8663e24d PZ |
9272 | raw_spin_unlock_irq(&rq->lock); |
9273 | } | |
9274 | } | |
9275 | ||
6fe1f348 | 9276 | void unregister_fair_sched_group(struct task_group *tg) |
029632fb | 9277 | { |
029632fb | 9278 | unsigned long flags; |
6fe1f348 PZ |
9279 | struct rq *rq; |
9280 | int cpu; | |
029632fb | 9281 | |
6fe1f348 PZ |
9282 | for_each_possible_cpu(cpu) { |
9283 | if (tg->se[cpu]) | |
9284 | remove_entity_load_avg(tg->se[cpu]); | |
029632fb | 9285 | |
6fe1f348 PZ |
9286 | /* |
9287 | * Only empty task groups can be destroyed; so we can speculatively | |
9288 | * check on_list without danger of it being re-added. | |
9289 | */ | |
9290 | if (!tg->cfs_rq[cpu]->on_list) | |
9291 | continue; | |
9292 | ||
9293 | rq = cpu_rq(cpu); | |
9294 | ||
9295 | raw_spin_lock_irqsave(&rq->lock, flags); | |
9296 | list_del_leaf_cfs_rq(tg->cfs_rq[cpu]); | |
9297 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
9298 | } | |
029632fb PZ |
9299 | } |
9300 | ||
9301 | void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, | |
9302 | struct sched_entity *se, int cpu, | |
9303 | struct sched_entity *parent) | |
9304 | { | |
9305 | struct rq *rq = cpu_rq(cpu); | |
9306 | ||
9307 | cfs_rq->tg = tg; | |
9308 | cfs_rq->rq = rq; | |
029632fb PZ |
9309 | init_cfs_rq_runtime(cfs_rq); |
9310 | ||
9311 | tg->cfs_rq[cpu] = cfs_rq; | |
9312 | tg->se[cpu] = se; | |
9313 | ||
9314 | /* se could be NULL for root_task_group */ | |
9315 | if (!se) | |
9316 | return; | |
9317 | ||
fed14d45 | 9318 | if (!parent) { |
029632fb | 9319 | se->cfs_rq = &rq->cfs; |
fed14d45 PZ |
9320 | se->depth = 0; |
9321 | } else { | |
029632fb | 9322 | se->cfs_rq = parent->my_q; |
fed14d45 PZ |
9323 | se->depth = parent->depth + 1; |
9324 | } | |
029632fb PZ |
9325 | |
9326 | se->my_q = cfs_rq; | |
0ac9b1c2 PT |
9327 | /* guarantee group entities always have weight */ |
9328 | update_load_set(&se->load, NICE_0_LOAD); | |
029632fb PZ |
9329 | se->parent = parent; |
9330 | } | |
9331 | ||
9332 | static DEFINE_MUTEX(shares_mutex); | |
9333 | ||
9334 | int sched_group_set_shares(struct task_group *tg, unsigned long shares) | |
9335 | { | |
9336 | int i; | |
9337 | unsigned long flags; | |
9338 | ||
9339 | /* | |
9340 | * We can't change the weight of the root cgroup. | |
9341 | */ | |
9342 | if (!tg->se[0]) | |
9343 | return -EINVAL; | |
9344 | ||
9345 | shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES)); | |
9346 | ||
9347 | mutex_lock(&shares_mutex); | |
9348 | if (tg->shares == shares) | |
9349 | goto done; | |
9350 | ||
9351 | tg->shares = shares; | |
9352 | for_each_possible_cpu(i) { | |
9353 | struct rq *rq = cpu_rq(i); | |
9354 | struct sched_entity *se; | |
9355 | ||
9356 | se = tg->se[i]; | |
9357 | /* Propagate contribution to hierarchy */ | |
9358 | raw_spin_lock_irqsave(&rq->lock, flags); | |
71b1da46 FW |
9359 | |
9360 | /* Possible calls to update_curr() need rq clock */ | |
9361 | update_rq_clock(rq); | |
17bc14b7 | 9362 | for_each_sched_entity(se) |
029632fb PZ |
9363 | update_cfs_shares(group_cfs_rq(se)); |
9364 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
9365 | } | |
9366 | ||
9367 | done: | |
9368 | mutex_unlock(&shares_mutex); | |
9369 | return 0; | |
9370 | } | |
9371 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
9372 | ||
9373 | void free_fair_sched_group(struct task_group *tg) { } | |
9374 | ||
9375 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) | |
9376 | { | |
9377 | return 1; | |
9378 | } | |
9379 | ||
8663e24d PZ |
9380 | void online_fair_sched_group(struct task_group *tg) { } |
9381 | ||
6fe1f348 | 9382 | void unregister_fair_sched_group(struct task_group *tg) { } |
029632fb PZ |
9383 | |
9384 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
9385 | ||
810b3817 | 9386 | |
6d686f45 | 9387 | static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task) |
0d721cea PW |
9388 | { |
9389 | struct sched_entity *se = &task->se; | |
0d721cea PW |
9390 | unsigned int rr_interval = 0; |
9391 | ||
9392 | /* | |
9393 | * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise | |
9394 | * idle runqueue: | |
9395 | */ | |
0d721cea | 9396 | if (rq->cfs.load.weight) |
a59f4e07 | 9397 | rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); |
0d721cea PW |
9398 | |
9399 | return rr_interval; | |
9400 | } | |
9401 | ||
bf0f6f24 IM |
9402 | /* |
9403 | * All the scheduling class methods: | |
9404 | */ | |
029632fb | 9405 | const struct sched_class fair_sched_class = { |
5522d5d5 | 9406 | .next = &idle_sched_class, |
bf0f6f24 IM |
9407 | .enqueue_task = enqueue_task_fair, |
9408 | .dequeue_task = dequeue_task_fair, | |
9409 | .yield_task = yield_task_fair, | |
d95f4122 | 9410 | .yield_to_task = yield_to_task_fair, |
bf0f6f24 | 9411 | |
2e09bf55 | 9412 | .check_preempt_curr = check_preempt_wakeup, |
bf0f6f24 IM |
9413 | |
9414 | .pick_next_task = pick_next_task_fair, | |
9415 | .put_prev_task = put_prev_task_fair, | |
9416 | ||
681f3e68 | 9417 | #ifdef CONFIG_SMP |
4ce72a2c | 9418 | .select_task_rq = select_task_rq_fair, |
0a74bef8 | 9419 | .migrate_task_rq = migrate_task_rq_fair, |
141965c7 | 9420 | |
0bcdcf28 CE |
9421 | .rq_online = rq_online_fair, |
9422 | .rq_offline = rq_offline_fair, | |
88ec22d3 | 9423 | |
12695578 | 9424 | .task_dead = task_dead_fair, |
c5b28038 | 9425 | .set_cpus_allowed = set_cpus_allowed_common, |
681f3e68 | 9426 | #endif |
bf0f6f24 | 9427 | |
83b699ed | 9428 | .set_curr_task = set_curr_task_fair, |
bf0f6f24 | 9429 | .task_tick = task_tick_fair, |
cd29fe6f | 9430 | .task_fork = task_fork_fair, |
cb469845 SR |
9431 | |
9432 | .prio_changed = prio_changed_fair, | |
da7a735e | 9433 | .switched_from = switched_from_fair, |
cb469845 | 9434 | .switched_to = switched_to_fair, |
810b3817 | 9435 | |
0d721cea PW |
9436 | .get_rr_interval = get_rr_interval_fair, |
9437 | ||
6e998916 SG |
9438 | .update_curr = update_curr_fair, |
9439 | ||
810b3817 | 9440 | #ifdef CONFIG_FAIR_GROUP_SCHED |
ea86cb4b | 9441 | .task_change_group = task_change_group_fair, |
810b3817 | 9442 | #endif |
bf0f6f24 IM |
9443 | }; |
9444 | ||
9445 | #ifdef CONFIG_SCHED_DEBUG | |
029632fb | 9446 | void print_cfs_stats(struct seq_file *m, int cpu) |
bf0f6f24 | 9447 | { |
bf0f6f24 IM |
9448 | struct cfs_rq *cfs_rq; |
9449 | ||
5973e5b9 | 9450 | rcu_read_lock(); |
c3b64f1e | 9451 | for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) |
5cef9eca | 9452 | print_cfs_rq(m, cpu, cfs_rq); |
5973e5b9 | 9453 | rcu_read_unlock(); |
bf0f6f24 | 9454 | } |
397f2378 SD |
9455 | |
9456 | #ifdef CONFIG_NUMA_BALANCING | |
9457 | void show_numa_stats(struct task_struct *p, struct seq_file *m) | |
9458 | { | |
9459 | int node; | |
9460 | unsigned long tsf = 0, tpf = 0, gsf = 0, gpf = 0; | |
9461 | ||
9462 | for_each_online_node(node) { | |
9463 | if (p->numa_faults) { | |
9464 | tsf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 0)]; | |
9465 | tpf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 1)]; | |
9466 | } | |
9467 | if (p->numa_group) { | |
9468 | gsf = p->numa_group->faults[task_faults_idx(NUMA_MEM, node, 0)], | |
9469 | gpf = p->numa_group->faults[task_faults_idx(NUMA_MEM, node, 1)]; | |
9470 | } | |
9471 | print_numa_stats(m, node, tsf, tpf, gsf, gpf); | |
9472 | } | |
9473 | } | |
9474 | #endif /* CONFIG_NUMA_BALANCING */ | |
9475 | #endif /* CONFIG_SCHED_DEBUG */ | |
029632fb PZ |
9476 | |
9477 | __init void init_sched_fair_class(void) | |
9478 | { | |
9479 | #ifdef CONFIG_SMP | |
9480 | open_softirq(SCHED_SOFTIRQ, run_rebalance_domains); | |
9481 | ||
3451d024 | 9482 | #ifdef CONFIG_NO_HZ_COMMON |
554cecaf | 9483 | nohz.next_balance = jiffies; |
029632fb | 9484 | zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); |
029632fb PZ |
9485 | #endif |
9486 | #endif /* SMP */ | |
9487 | ||
9488 | } |